Electrostatic copying apparatus

ABSTRACT

An electrostatic copying apparatus having a semiautomatic document supplying and discharging device and a sorter in addition to its main body. The main body of the apparatus includes a rotatable photosensitive member, a device for forming a latent electrostatic image on the photosensitive member, a developer, a transfer device, a device for conveying a copying paper, a cleaner and a heat fixing device. Various improvements have been made in the manner of controlling cleaning, the manner of controlling the delivery of a copying paper, the manner of controlling troubleshooting and display, the manner of controlling interrupting copying, the manner of controlling heating, the manner of distribution electric power, etc. A heat fixing device includes an electrical heater having a heat controller for controlling energization and deenergization of the heater on the basis of detected temperature. An electrical power saving unit has a manually operable power saving switch which produces a power saving signal to which the heat controller is partially responsive.

This is a division of application Ser. No. 451,184, filed Dec. 20, 1982,now U.S. Pat. No. 4,551,009, issued Nov. 5, 1985.

FIELD OF THE INVENTION

This invention relates to certain improvements in an electrostaticcopying apparatus.

DESCRIPTION OF THE PRIOR ART

Electrostatic copying apparatuses of various types have been suggestedand come into commercial acceptance in the past. In a typicalelectrostatic copying apparatus, a rotating drum having a photosensitivemember disposed on its peripheral surface is provided, and around therotating drum are located a charging zone, an exposure zone, adeveloping zone, a transfer zone, a peeling zone and a cleaning zone inthis order in the rotating direction of the rotating drum. In thecharging zone, the photosensitive member is charged to a specifiedpolarity by the action of a charging corona discharge device, and in theexposure zone, the image of a document to be copied is projected ontothe photosensitive member, whereby the charge on the photosensitivemember is selectively eliminated and a latent electrostatic image isformed on the photosensitive member. In the developing zone, a toner isapplied to the latent electrostatic image on the photosensitive memberby, for example, a developing means of the magnetic brush type todevelop the latent electrostatic image into a toner image. In thetransfer zone, the toner image on the photosensitive member istrnsferred onto a copying paper conveyed through the transfer zone. Inthe peeling zone, the copying paper contacted with the photosensitivemember in the transfer zone is peeled off from the phosotsensitivemember. In the cleaning zone, the toner remaining on the photosensitivemember after the transfer is removed by, for example, the action of acleaning blade to be in contact with the photosensitive member. In themeantime, the copying paper having the toner image transferred thereto,which has been peeled from the photosensitive member in the peelingzone, is passed through a fixing device such as a heat fixing devicewhereby the toner image is fixed to the copying paper in the fixingdevice.

As is well known, the electrostatic copying apparatus described abovefrequently has a semi-automatic document supplying and dischargingdevice and a sorter annexed thereto. The semi-automatic documentsupplying and discharging device feeds a document inserted by hand intoits document introducing section to a document supporting transparentplate disposed on the upper surface of the housing of the main body ofthe electrostatic copying apparatus. The sorter is actuated whenmultiple copies are to be formed from each of a plurality of documents,and sorts the copying papers having a fixed toner image which aredischarged from the main body of the electrostatic copying apparatus.

The conventional electrostatic copying apparatus, however, has variousinconveniences or defects in regard to the following operations anddevices which will be described in detail hereinafter.

(1) Control of the positioning of the cleaning blade adapted to beselectively positioned at its operating position at which it is broughtinto contact with the photosensitive member and at its non-operatingposition at which it is moved away from the photosensitive member, whenthe cleaning blade is used with the magnetic brush-type developingmeans;

(2) Control of continued delivery of copying papers in response to thecopying process performed continuously, when there is used a copyingpaper feed device loaded with a copying paper cassette containing aplurality of stacked paper sheets;

(3) Display control for making the operator aware that the electrostaticcopying apparatus should not perform the copying process;

(4) Displaying of the number of copying papers to be removed by hand(i.e., copying papers present in and outside the paper conveyingpassage), when a trouble occurs in the conveying of paper;

(5) Counting of the number of copying cycles when a trouble occurs inthe transfer of a document in a semi-automatic document supplying anddischarging device annexed to the electrostatic copying apparatus;

(6) Realization of interruption in the copying process when thesemi-automatic document supplying and discharging device is annexed tothe electrostatic copying apparatus;

(7) Control based on the temperature of the surface or its vicinity ofthe photosensitive member;

(8) Control of the energization or deenergization of an electric heatingmeans when a heat-fixing device containing the electronic heating meansis used;

(9) Control of distributing an electric power when the heat-fixingdevice having the electric heating means is used; and

(10) electrical detecting devices for temperature, etc.

SUMMARY OF THE INVENTION

The general object of this invention is to remove the variousinconveniences and defects existing in conventional electrostaticcopying apparatuses and to improve such apparatuses in various respects.

Various specific objects of this invention will become apparent from thefollowing detailed description of the invention taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of the copying apparatusconstructed in accordance with this invention in a condition in which asemi-automatic document supplying and discharging device is held in itsoperating position;

FIG. 2 is a perspective view of the copying apparatus of FIG. 1 in acondition in which the semi-automatic document supplying and dischargingdevice is held in its non-operating position;

FIG. 3 is a simplified sectional view of the copying apparatus shown inFIG. 1;

FIG. 4 is a simplified partial sectional view showing a rotating drumand its vicinity in the copying apparatus shown in FIG. 1;

FIG. 5 is a simplified partial sectional view showing a paper feeddevice in the coyping apparatus shown in FIG. 1;

FIG. 6 is a simplified partial view showing a panel in the copyingapparatus shown in FIG. 1;

FIG. 7 is a simplified block diagram showing processing means andvarious detecting means for feeding signals thereto;

FIG. 8 is a flow chart showing the manner of controlling cleaning in thecopying apparatus shown in FIG. 1;

FIG. 9 is a flow chart showing the manner of controlling the supply of acopying paper in the copying apparatus shown in FIG. 1;

FIG. 10 is a flow chart showing the manner of controlling asemi-automatic document supplying and discharging device in the copyingapparatus shown in FIG. 1;

FIGS. 11-A to 11-D are flow charts showing the manner of controllingtrouble shooting and display in the copying apparatus shown in FIG. 1;

FIGS. 12-A to 12-D are simplified views showing examples of displaymeans in the copying apparatus shown in FIG. 1;

FIG. 13 is a schematic view showing a control system for controlling acharging corona discharge device and an electric heating means in thecopying apparatus shown in FIG. 1;

FIG. 14 is a schematic view showing a control system for controlling anelectrical heating means of a heat fixing device in the copyingapparatus shown in FIG. 1;

FIG. 15 is a flow chart showing the mode of controlling heating of aheat fixing device in the copying apparatus shown in FIG. 1;

FIG. 16 is a diagram showing changes with time of the temperature of theheat fixing device in the copying apparatus shown in FIG. 1;

FIG. 17 is a flow chart showing the mode of controlling electric powerin the copying apparatus shown in FIG. 1;

FIG. 18 is a diagram showing the waveform of a current supplied to anelectrical heating means of a heat fixing device in the copyingapparatus shown in FIG. 1;

FIG. 19 is a diagram showing a modified example of the waveform of acurrent supplied to an electrical heating means of a heat fixing device;

FIG. 20 is a circuit diagram showing a detecting device for a heatfixing device in the copying apparatus shown in FIG. 1;

FIG. 21 is a diagram showing signals delivered from a switching controlmeans in the detecting device shown in FIG. 20;

FIG. 22 is a circuit diagram showing a modified example of the detectingdevice shown in FIG. 20; and

FIG. 23 is a diagram showing signals delivered from a switching controlmeans in the modified example of the detecting device of FIG. 22.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will be described in detail with reference to theaccompanying drawings.

GENERAL OUTLINE OF COPYING APPARATUS

The outline of the construction of one embodiment of an electrostaticcopying apparatus improved variously in accordance with this inventionwill be described.

With reference to FIGS. 1 and 2, the illustrated electrostatic copyingapparatus has a main body shown generally at 2 which includes a nearlyrectangularly-shaped housing 4. The copying apparatus further includes asemi-automatic document supplying and discharging device shown generallyat 6 and annexed to the upper surface of the housing 4, a documentholding mechanism shown generally at 8 and annexed similarly to theupper surface of the housing 4, and a sorter shown generally at 10 andannexed to one side surface of the housing 4.

The semi-automatic document supplying and discharging device 6 includesa stationary support frame structure 14 mounted on the top of thehousing 4 adjacent to one side edge of a transparent plate 12 (FIG. 3)disposed on the top of the housing 4, and a movable main frame structure16 mounted for free turning about an axis extending along said one sideedge of the transparent plate 12 and between an operating position (theposition shown in FIG. 1) at which it covers the transparent plate 12and a non-operating position (the position shown in FIG. 2 which isdisplaced about 90° from the above operating position in a clockwisedirection as viewed from the right bottom in FIGS. 1 and 2) at which itbrings the transparent plate 12 to view. On the other hand, the documentholding device 8 is mounted such that it is free to turn between anoperating position at which it covers the transparent plate 12 (theposition shown in FIG. 2) and a non-operating position (the positionshown in FIG. 1 displaced about 90° from the above operating position asviewed from the right top in FIGS. 1 and 2) at which it brings thetransparent plate 12 to view, and about an axis extending along theother side edge of the transparent plate 12 which extends substantiallyat right angles to the pivot axis of the main frame structure 16 of thesemi-automatic document supplying and discharging device 6. Inpositioning a document to be copied on the transparent plate 12 byutilizing the semi-automatic document supplying and discharging device 6in the above-illustrated electrostatic copying apparatus, the documentholding device 8 is brought to the non-operating position and the mainframe structure 16 of the semi-automatic document supplying anddischarging device 6 is brought to the operating position. When thedocument to be copied is to be positioned on the transparent plate 12 bya manual operation without utilizing the semi-automatic device 6 (forexample, when the document is a thick one such as a book or one havingrelatively high rigidity, such as a thick sheet of paper or a metalplate), the operator brings the main frame structure 16 of thesemi-automatic device 6 to the non-operating position, then places thedocument on the desired site of the transparent plate 12, turns thedocument holding device 8 to the above operating position, and thuscovers the transparent plate 12 and the document thereon with thedocument holding device 8. In withdrawing the document after the end ofa copying cycle, the document holding device 8 is turned to thenon-operating position.

With reference to FIG. 3, the main body 2 of the copying apparatus willbe described. The transparent plate 12 on which to place a document tobe copied is disposed on the upper surface of the housing 4. Acylindrical rotating drum 18 is rotatably mounted substantiallycentrally at the lower part of the housing 4, and an endlessphotosensitive member 20 is provided on the peripheral surface of therotating drum 18. It is also possible to use an endless belt elementknown to those skilled in the art in place of the rotating drum 18 andto dispose the photosensitive member on the surface of the endless beltelement. With reference to FIG. 4 together with FIG. 3, around therotating drum to be rotated in the direction of an arrow 22 are locateda charging zone 24, an exposure zone 26, a developing zone 28, atransfer zone 30, a peeling zone 32 and a cleaning zone 34 in thissequence as viewed in the rotating direction of the rotating drum 18.The charging zone 24 and the exposure zone 26, taken together, form alatent electrostatic image-forming zone 36. A charging corona dischargedevice 38 is disposed in the charging zone 24, and a developing means 40of the magnetic brush type in any desired form is disposed in thedeveloping zone 28. A transfer corona discharge device 42 is disposed inthe transfer zone 30, and peeling corona discharge devices 44 and 46 aredisposed in the peeling zone 32. In the cleaning zone 34, a cleaningblade 48 is provided.

A paper conveying means shown generally at 50 is provided in the lowerportion of the housing 4. A paper feed device 52 is disposed at theupstream end portion (the right end portion in FIG. 3) of the paperconveying means 50. With reference to FIG. 5 taken in conjunction withFIG. 3, the paper feed device 52 includes a first cassette-receivingsection 54a and a second cassette-receiving section 54b located aboveit. The first cassette-receiving section 54a receives a paper cassette58a containing a plurality of stacked copying paper sheets 56a, and thesecond cassette-receiving section 54b receives a paper cassette 58bcontaining a plurality of stacked copying paper sheets 56b. A firstpaper supply means 60a and a second paper supply means 60b are providedrespectively in the first cassette-receiving section 54a and the secondcassette-receiving section 54b. The first paper supply means 60a iscomprised of a support shaft 62a and a supply roller 64a fixed thereto,and the second paper supply means 60b is comprised of a support shaft62b and a supply roller 64b fixed thereto. To the firstcassette-receiving section 54a is annexed a first paper introducingpassage 70a defined by a pair of guide plates 66 and 68. Likewise, asecond paper introducing passage 70b defind by a pair of guide plates 72and 74 and a pair of guide plates 76 and 78 is annexed to the secondcassette-receiving section 54b. A pair of supply assisting rollers 80and 82 are provided between the pair of guide plates 72 and 74 and thepair of guide plates 76 and 78. Further, with reference to FIG. 3, apair of conveyor rollers 84 and 86 are provided at a point of junctionof the first paper introducing passage 70a and the second paperintroducing passage 70b, and following this pair of conveyor rollers 84and 86, a pair of guide plates 88 and 90, a pair of conveyor rollers 92and 94 and a pair of guide plates 96 and 98 are provided. The downstreamend of the pair of guide plates 96 and 98 extend to the upstream end ofthe transfer zone 30. A conveyor belt mechanism 100 is disposeddownstream of the peeling zone 32 as viewed in the paper conveyingdirection. A guide plate 102 is disposed downstream of the conveyor beltmechanism 100, and a heat-fixing device 104 is disposed downstream ofthe guide plate 102. The heat-fixing device 104 is comprised of aheating roller 108 having an electrical heating means 106 therein, and apress-contact roller 110 cooperating with the heating roller 108. A pairof guide plates 112 and 114 are disposed downstream of the heat-fixingdevice 104. In the paper conveying means 50 of the aforesaidconstruction, a copying paper is supplied through the first paperintroducing passage 70a from the paper cassette 58a in the paper feeddevice 52 or through the second paper introducing passage 70b from thepaper cassette 58b (the paper feed device 52 will be described in moredetail hereinafter). and conveyed to the transfer zone 30 by the pair ofconveyor rollers 84 and 86, the pair of guide plates 88 and 90, the pairof conveyor rollers 92 and 94, and the pair of guide plates 96 and 98.The paper is brought into contact with the photosensitive member 20 onthe rotating drum 18 in the transfer zone 30, then peeled from thephotosensitive member 20 in the peeling zone 32, thereafter conveyed bythe conveyor belt mechanism 100, introduced into the heat-fixing device104 via the guide plate 102, and thereafter passed through the pair ofguide plates 112 and 114 and discharged into the sorter 10.

In the upper portion of the housing 4, there is provided an optical unitgenerally shown at 116 for scanning and exposing a document on thetransparent plate 8 and projecting its image onto the photosensitivemember 20 on the rotating drum 18 in the exposure zone 26. The opticalunit 116 has a document illuminating lamp 118 for illuminating thedocument placed on the transparent plate 8, a first reflecting mirror120 for projecting the reflected light from the document onto thephotosensitive member 20, a second reflecting mirror 122, a thirdreflecting mirror 124, a lens assembly 126 and a fourth reflectingmirror 128. During scanning and exposure, the document illuminating lamp118 and the first reflecting mirror 120 which are mounted on a commonsupport frame 130 are moved substantially horizontally at apredetermined speed V from their initial position shown by the solidline to required positions (for example, maximum scanning-exposuretermination positions shown by the two-dot chain line), and the secondreflecting mirror 122 and the third reflecting mirror 124 which aremounted on a common support frame 132 are moved at a speed one half ofthe aforesaid speed (i.e., 1/2V) from their initial positions shown bythe solid line to required positions (for example, maximumscanning-exposure termination positions shown by the two-dot chainline). At this time, the light reflected from the document illuminatedby the document illuminating lamp 118 is reflected successively by thefirst reflecting mirror 120, the second reflecting mirror 122 and thethird reflecting mirror 124 and reaches the lens assembly 126.Thereafter, it is reflected by the fourth reflecting mirror 126 andreaches the photosensitive member 20 in the exposure zone 26. When thescanning exposure is terminated, the document illuminating lamp 118, thefirst relfecting mirror 120, the second reflecting mirror 122 and thethird reflecting mirror 124 are returned to their initial positionsshown by the solid line.

In the main body 2 of the copying apparatus described above, while therotating drum is rotated in the direction of arrow 22, the chargingcorona discharge device 38 substantially uniformly charges thephotosensitive member 20 to a specified polarity in the charging zone24, and thereafter in the exposure zone 26, the optical unit 116projects the image of the document to eliminate the cahrge on thephotosensitive member 20 selectively, whereby a latent electrostaticimage corresponding to the document is formed on the photosensitivemember 20. Thereafter, the developing means 40 applies a toner to thelatent electrostatic image on the photosensitive member 20 to developthe latent electrostatic image to a toner image. Then, in the transferzone 30, a copying paper conveyed by the paper conveying means 50 isbrought into contact with the photosensitive member 20, and by theaction of the transfer corona discharge device 42, the toner image onthe photosensitive member 20 is transferred to the paper. Subsequently,in the peeling zone 32, the copying paper is peeled from thephotosensitive member 20 by the action of the peeling corona dischargedevices 44 and 46. The copying paper having the toner image transferredthereto is then conveyed to the heat-fixing device 104 where the tonerimage is fixed to the copying paper. The paper is then discharged intothe sorter 10. In the meantime, the photosensitive member 20 continuesto rotate, and the toner remaining on the photosensitive member 20 afterthe transfer operation is removed from it by the action of the cleaningblade 48 in the cleaning zone 34 or by the action of the magneticbrush-type developing means 40 in the developing zone 28 (the removal ofthe residual toner from the photosensitive member 20 will be describedin more detail hereinafter).

With reference to FIG. 3, the semi-automatic document supplying anddischarging device 6 will be generally described. The semi-automaticdevice 6 includes the stationary support frame structure 14 and themovable main frame structure 16, as already stated above. As can be seenfrom FIG. 3, the support frame structure 14 is mounted on one endportion (the right end portion in FIG. 3) of the top of the housing 4adjacent to one side edge of the transparent plate 12 fixed to the topof the housing 4. A shaft 130 extending in the front and rear direction(a direction perpendicular to the sheet surface in FIG. 3) is rotatablymounted on the support frame structure 10. One end portion (the rightend portion in FIG. 3) of the main frame structure 16 is mountedpivotally on the shaft 130. The main frame structure 16 has an upperplate 132 and a lower plate 134. The upper plate 132 defines asubstantially flat, document receiving surface 136 on the top side ofthe main frame structure 16. As will be described below, the documentreceiving surface 136 receives the document discharged from the mainframe structure 16. Preferably, a restraining member 138 for restrainingthe leading edge of the document discharged onto the receiving surface136 to put it in order is secured to the top side of the upper plate 132in such a manner that its position can be adjusted according to the sizeof the document. When the main frame structure 16 is held at theoperating position as shown in FIG. 3, the lower plate 134 defining theunder side of the main frame 16 is positioned slightly upwardly of, andsubstantially parallel to, the transparent plate 12 to define a mainportion 142 of a document conveying passage 140 between it and the topside of the transparent plate 12. The document conveying passage 140additionally has an introducing portion 144 located upstream of the mainportion 142 and a curved discharging portion 146 connecting the mainportion 142 to the document receiving surface 136. The introducingportion 144 is defined in the support frame structure 14, and the curveddischarging portion 146 is defined in the other end portion, i.e. thefree end portion (the left end portion in FIG. 3) of the main framestructure 16. The introducing portion 144 of the document conveyingpassage 140 is defined between a lower guide plate 148 and two upperguide plates 150 and 152. A document stand 154 is annexed to theupstream side of the support frame structure 14. The surface of thedocument stand 154 defines a guide surface 156 for manually positioninga document to be copied, which joins the upstream end of the introducingportion 144 of the document conveying passage 140. On the surface of thedocument stand 154 is formed a guiding protrusion 158 which restrainsthe position of one side edge of a document placed on the guide surface156 for insertion into the introducing portion 144 of the conveyingpassage 140 and thus restricts the position of the document in thewidthwise direction. In the introducing portion 144 of the documentconveying passage 140, they are further provided a conveying roller unit160 for conveying the document inserted into the introducing portion 144to the main portion 142 through the introducing portion 144 and a firstregulating member 162 for regulating the position of the document, whichprojects into the introducing portion 144 at a position downstream ofthe conveying roller unit 160 and can arrest the advancing of thedocument passing through the introducing portion 144. The conveyingroller unit 160 is comprised of a driven roller 164 and a followerroller 166. A solenoid 168 is provided in relation to the conveyingroller unit 160 and the first regulating member 162. When the solenoid168 is in the deenergized state, the follower roller 166 is positionedbelow the lower guide plate 148 away from the driven roller 164, and thefirst regulating member 162 projects into the introducing portion 144through an opening formed in the lower guide plate 148 to hamper theadvancing of the document. On the other hand, when the solenoid isenergized, the follower roller 166 projects into the introducing portionthrough the opening formed in the lower guide plate 148 and is pressedagainst the driven roller 164, and the first regulating member 162 movesaway from the introducing portion 144 and is located below the lowerguide plate 148 to permit the advancing of the document.

The semi-automatic document supplying and discharging device 6 furtherincludes a conveyor belt mechanism 170 for conveying the document, whichhas been sent to the main portion 142 of the conveying passage 140 fromthe introducing portion 144, through the main portion 142, furtherconveying it from there through the curved discharging portion 146 anddischarging it onto the document receiving surface 136. The conveyorbelt mechanism 170 has a plurality of laterally spaced endless belts 172(only one of which is shown in FIG. 3) which are wrapped about a drivenwheel 174 mounted on the shaft 130 and follower wheels 180 and 182mounted respectively on shafts 176 and 178 mounted on the free endportion (the left end portion in FIG. 3) of the main frame structure 16.A tension roller 184 and a tension rod 186 for maintaining the endlessbelts 172 taut are also provided. The lower travelling section of theendless belts 172 extends between the lower plate 134 and thetransparent plate 12. The shaft 130 on which the driven wheel 174 ismounted is drivingly connected to an electric motor 188 mounted on thesupport frame structure 14, and rotated clockwise in FIG. 3 when themotor 188 is energized. In the intermediate portion of the main portion142 of the conveying passage 140 is provided a hemispherical pressingpiece 190 projecting downwardly through an opening formed in the lowerplate 134 for forcing the endless belts 172 downwardly. The secondregulating member 192 and a rotatably mounted pressing roller 194 areprovided in the downstream end portion of the main portion 142. Asolenoid 196 is provided in relation to the second regulating member 192and the pressing roller 194. When the solenoid 196 is in the deenergizedstate, the second regulating member 192 projects into the main portion142 of the conveying passage 140 through the opening formed in the lowerplate 134 to hamper the advancing of the document, and the pressingroller 194 is located above the lower plate 134. On the other hand, whenthe solenoid 196 is energized, the second regulating member 192 movesaway from the main portion 142 and is located above the lower plate 134,while the pressing roller 194 projects downwardly through the openingformed in the lower plate 134 to force the endless belts 172 downwardly.In the curved discharging portion 146 of the conveying passage 140, aroller 198 located opposite to the wheel 180 and a roller 200 locatedopposite to the wheel 182 are rotatably mounted. The rollers 198 and 200cooperate with the endless belts 172.

Since the semi-automatic document supplying and discharging device 6described above is substantially the same as the semi-automatic documentsupplying and discharging device disclosed in Japanese Laid-Open PatentPublication No. 161874/1982 (corresponding to U.S. Pat. No. 4,465,272and European Patent Application No. 82102455.1), the disclosure of theaforesaid U.S. Pat. No. 4,465,272 is cited herein as reference in lieuof a detailed description of the device 6.

The sorter 10 has a frame structure 202 having an open front side. Theinside of the frame structure 202 includes a plurality of verticallystacked bins 204 and a moving means 206 for suitably moving the bins204. When the copying process is to be repeated a number of times forthe same document, after a copy (i.e., a copying paper having a fixedtoner image) formed in a given copying cycle is received in thelowermost bin 204, the moving means 206 immediately moves downwardlythat bin 204 which exists immediately above the aforesaid bin so as toreceive a copy to be formed in the next copying cycle. After a copy inthe final cycle of the copying process is received in a specified bin204, the moving means 206 raises those bins 204 expecting the lowermostbin 204 to return them to the initial positions shown in FIG. 3. Thesorter 10 itself may be substantially the same as the sorter disclosedin the specification of Japanese Patent Application No. 162205/1981, anda detailed description of the structure of the sorter 10 itself isomitted in this specification.

DETECTING MEANS, MANUALLY OPERABLE SWITCHES, DISPLAY MEANS, ETC.

With reference to FIGS. 3 and 5, in the paper feed device 52 in the mainbody 2 of the electrostatic copying apparatus in accordance with thisinvention, either one of three types of paper cassettes containingcopying paper sheets according to JIS standards A3, A4 and A5 is mountedon the first cassette-receiving section 54a, and either one of threetypes of paper cassettes containing paper sheets according to JISstandards B4, B5 and B6 is mounted on the second cassette-receivingsection 54b. In the first cassette-receiving section 54a and the secondcassette-receiving section 54b, discriminating means 208a and 208b arerespectively provided for determining which of the three types of thepaper cassettes has been mounted. Each of the discriminating means 208aand 208b may be comprised of two reed switches disposed in spaced-apartrelationship in the widthwise direction. In this case, two permanentmagnets (not shown) are fixed to the opposite sides of the front surfaceof each of the A3 paper cassette containing paper sheets having a sizeA3 and the B4 paper cassette containing paper sheets having a size B4,for example; one permanent magnet is fixed to one side of the frontsurface of each of the A4 paper cassette containing paper sheets havinga size A4 and the B5 paper cassette containing paper sheets having asize B5; and one permanent magnet is fixed to one side of the frontsurface of each of the A5 paper cassette containing paper sheets havinga size A5 and the B6 paper cassette containing paper sheets having asize B6 which side is opposite to said one side of the front surface ofthe A4 or B5 paper cassette. Accordingly, when the A3 paper cassette isto be loaded on the first cassette-receiving section 54a, both of thetwo read switches constituting the discriminating means 208a are closed.When the A4 paper cassette is to be loaded therein, one of the two reedswitches is closed. Furthermore, when the A5 paper cassette is to beloaded, the other of the two reed switches is closed. Likewise, when theB4 paper cassette is to be loaded in the second cassette-receivingsection 54b, both of the two reed switches constituting thediscriminating means 208b are closed. When the B5 paper cassette is tobe loaded, one of the two reed switches is closed. Furthermore, when theB6 paper cassette is to be loaded, the other of the two reed switches isclosed.

Detecting means 210a and 210b for detecting the rotation or stopping ofthe shafts 62a and 62b are provided with respect to each of the shaft62a fixed to the supply roller 64a and the shaft 62b fixed to the supplyroller 64b in the paper feed device 52. The detecting means 210a and210b are comprised respectively of discs 212a and 212b fixed to one endportions of the shafts 62a and 62b and stationary photocouplers 214a and214b consisting of light emitting elements located on one side of thediscs 212a and 212b and light-receiving elements located on the othersides of the discs 212a and 212b. A number of cuts are formed atsuitable intervals in the circumferential direction in thecircumferential edge portion of each of the discs 212a and 212b. Wheneach of the shafts 62a and 62b is at rest, a cut or a portion betweencuts of each of the discs 212a and 212b exists continuously between thelight-emitting element and the light-receiving element of each of thephotocouplers 214a and 214b, and therefore the light-receiving elementof each of the photocouplers 214a and 214b is continuously maintained incondition for receiving light from the light-emitting element or for notreceiving it. On the other hand, when each of the shafts 62a and 62b isrotated, a cut and a portion between cuts of each of the discs 212a and212b alternately pass between the light-emitting element and the lightreceiving element of each of the photocouplers 214a and 214b, andtherefore, the light receiving element of each of the photocouplers 214aand 214b is alternately maintained in condition for not receiving lightfrom the light emitting element and for receiving it.

As clearly shown in FIG. 4, a paper detecting means 216 is provided inrelation to both of the first paper introducing passage 70a extendingfrom the first cassette-receiving section 58a and the second paperintroducing passage 70b extending from the second cassette-receivingsection 58b. The detecting means 216 includes a microswitch 220 havingan actuating arm 218, a detecting piece 224a mounted pivotally on ashaft 222a and projecting into the first paper introducing passage 70athrough an opening formed in the guide plate 66, and a detecting piece224b mounted pivotally on a shaft 222b and projecting into the secondpaper introducing passage 70b through an opening formed in the guideplate 76. When the leading edge of the copying paper 56a supplied to thefirst paper introducing passage 70a from the cassette 58a by the actionof the supply roller 64a rotated in the direction of the arrow comesinto contact with the nip position of the pair of conveyor rollers 84and 86 and consequently the copying paper 56a is bent as shown by thetwo-dot chain line, the detecting piece 224a is caused to pivotcountclockwise from its normal position shown in the drawing, and as aresult, a projection 226 of the detecting piece 224a acts on theactuating arm 218 of the microswitch 220 to close the microswitch 220.When the leading edge of the copying paper 56b supplied to the secondpaper introducing passage 70b from the paper cassette 58 b by the actionof the supply roller 64b rotated in the direction of the arrow andconveyed through the second paper introducing passage 70b by the actionof the pair of supply assisting rollers 80 and 82 rotated in thedirection of the arrow comes into contact with the nip position of thepair of conveyor rollers 84 and 86 and as a result, the copying paper56b is bent as shown by the two-dot chain line, the detecting piece 224bis caused to pivot clockwise from its normal position shows in thedrawing. As a result, a projection 228b of the detecting piece 224b actson the projection 228a of the detecting piece 224a to cause thedetecting piece 224a to pivot counterclockwise from its normal positionshown in the drawings. Finally, the projections 226 of the detectingpiece 224a acts on the actuating arm 218 of the microswitch 220 to closethe microseitch 220. A copying paper detecting means 228 is furtherprovided with regard to the second paper introducing passage 70b. Thedetecting means 228 is constructed of a microswitch having an actuatingarm 230 which projects into the second paper introducing passage 70bthrough the opening formed in the guide plate 74 upstream of the pair ofsupply assisting rollers 80 and 82. When the leading edge of the copyingpaper 56b supplied to the second paper introducing passage 70b from thecopying paper cassette 58b acts on the actuating arm 230, the detectingmeans 228 is closed, and when the trailing edge of the paper 56b goespast the actuating arm 230, the detecting means 228 is opened.

Again with reference to FIG. 3, the main body 2 of the electrostaticcopying apparatus further includes paper detecting means 232, 234 and236 which detect a copying paper conveyed by the paper conveying means50, at a position slightly downstream of the pair of conveyor rollers 84and 86, at a position slightly downstream of the peeling zone and at aposition slightly downstream of the heat-fixing device 104 (thedownstream end portion of the paper conveying passage in the main body2). The detecting means 232, 234 and 236 respectively have actuatingarms 238, 240 and 242 projecting into the paper conveying passage, andare closed when the leading edge of the copying paper acts on theactuating arms 238, 240 and 242 respectively and are opened when thetrailing edge of the copying paper goes past the actuating arms 238, 240and 242.

With reference to FIGS. 3 and 4, there is provided a paper wrappingdetecting means 244 which when a copying paper kept in contact with thephotosensitive member 20 on the rotating drum 18 in the transfer zone 30wraps about the photosensitive member 20 without being peeled from thephotosensitive member 20 in the peeling zone, detects the wrappingpaper. The detecting means 244 is comprised of a light emitting element246 for irradiating light onto the photosensitive member 20 at aposition slightly downstream of the peeling zone as viewed in therotating direction of the rotating drum 18, a light receiving elementfor receiving the light reflected from the photosensitive member 20, anda signal generator 250 electrically connected to the light receivingelement 248 for producing a paper wrapping signal when the intensity oflight received by the light receiving element is below a predeterminedthreshold value. The photosensitive member 20 itself has a highreflectance, and therefore when the paper is not wrapped about thephotosensitive member 20, the light receiving element 248 receives lighthaving a sufficient intensity. However, when the paper wraps about thephotosensitive member, the light receiving element 248 receives lighthaving an intensity below the threshold value and the signal generator250 produces a paper wrapping signal, because the copying paper has arelatively low reflectance. Preferably, the distance l₂ from the peelingzone 32 to the detecting position of the detecting means 244 as viewedin the rotating direction of the rotating drum 18 is substantially equalto the distance l₁ from the peeling zone 32 to the detecting position ofthe detecting means as viewed in the moving direction of the copyingpaper.

With reference to FIG. 3, the main body 2 of the electrostatic copyingapparatus further has disposed therein detecting means 252 and 254 fordetecting the support frame 132 on which the second reflecting mirror122 and the third reflecting mirror 124 in the optical unit 116 aremounted. Each of the detecting means 252 and 254 may be constructed of areed switch to be actuated by a permanent magnet fixed to the supportframe 132. The detecting means 252 detects the support frame 132 whenthe support frame 132 is at its initial position shown by the solidline. The detecting means 254 detects the support frame 132 and isclosed, when the support frame 132 moves from its initial position to aposition displaced to the right by a predetermined distance l₃.

A detecting means 256 which may be of any known form is disposed in thesorter 10, which when a trouble occurs (for example, when the bins 204are not moved as required), detects it and produces a signal.

In the semi-automatic document supplying and discharging device 6, thereis provided a document insertion detecting means 258 which detects adocument at that position of the introducing portion 144 of theconveying passage 140 which is slightly upstream of the documentadvancing arresting position of the first regulating means 162. Thedetecting means 258 may be comprised of a light emitting element 260located above the introducing portion 144 and a light receiving element262 located below the introducing portion 144. When a document isinserted by hand into the introducing portion 144, light projected ontothe light receiving element 262 from the light emitting element 260 isshut off by the document, whereupon the detecting means 258 produces adocument insertion signal. There is also provided a detecting means 264which detects a document at the position of the main portion 142 of theconveying passage 140 which is slightly upstream of the documentadvancing arresting position of the second regulating member 192. Thedetecting means 264 may be constructed of a light emitting element forprojecting light onto the transparent plate 12, a light receivingelement for receiving light reflected from the transparent plate 12, anda signal generator which produces a document detection signal when theintensity of the light received by the light receiving element fallsbelow a predetermined threshold value. Since the transparent plate 12itself has a high reflectance, the light receiving element receiveslight of a sufficient intensity when no document exists at the detectingposition. On the other hand, because the reflectance of the document isrelatively low, when the leading edge of the document arrives at thedetecting position, the light receiving element receives light having anintensity below the predetermined threshold value, and the signalgenerator produces a document detection signal. When the trailing edgeof the document goes past the detecting position, the light receivingelement again receives light having a sufficient intensity and the abovedocument detection signal disappears. Furthermore, a detecting means 266is provided which detects the document at the downstream end portion ofthe curved discharging portion 146 of the conveying passage 140. Thedetecting means 266 is comprised of a microswitch 270 having anactuating arm 268, and a detecting piece 272 mounted pivotally by asupporting pin 271. One end portion of the detecting piece 272 projectsinto the curved discharging portion 146. When the leading edge of thedocument acts on one end portion of the detecting piece 272, thedetecting piece 272 is caused to pivot counterclockwise from its normalposition shown in the drawing. As a result, the other end portion of thedetecting piece 272 acts on the actuating arm 268 of the microswitch 270to close the microswitch 270. When the trailing edge of the documentgoes past the one end portion of the detecting piece 272, the detectingpiece 272 returns to its normal position shown in the drawings, and themicroswitch 270 is opened.

In the illustrated copying apparatus, there are further provided knownsuitable detecting means (inclusively designated by numeral 275) whichdetect a disorder in various other constituent elements such as thedocument illuminating lamp 118 (FIG. 3), the electrical heating means106 (FIG. 3) in the heat-fixing means, and the electrical heating means273 (FIG. 4) for heating the photosensitive member 20. The electricalheating means 273 (FIG. 4) for heating the photosensitive member 20 willbe described further hereinafter. In the illustrated copying apparatus,a temperature detecting means 277 (FIG. 3) for detecting the temperatureof the heat-fixing device 104 and a temperature detecting means 279(FIG. 4) for detecting the temperature of the surface or its vicinity ofthe photosensitive member 20 are further provided. Detecting devices 281and 283 respectively including the temperature detecting means 277 and279 produce not only a temperature signal but also a signal showing adisorder which occurs in the temperature detecting means 277 and 279, aswill be described in detail hereinbelow.

With reference to FIGS. 1 and 2, a key card inserting section 274 isprovided at the front end portion of the upper surface of the housing 4of the main body 2 of the copying apparatus. A given key card 276 isinserted into the key card inserting section by an operator. In the keycard inserting section 274 is provided a signal producing means 278which when the key card 276 is inserted, detects it and produces acopying process performance permission signal (FIG. 7). As will bedescribed hereinafter, in the illustrated electrostatic copying machine,the copying process cannot be performed unless the operator inserts thekey card 276 into the key card inserting section 274 thereby producingthe aforesaid signal for the permission of the performance of thecopying process, as will be described in more detail hereinafter. Thisprevents any unauthorized person from operating the copying apparatusand obtaining copies. Adjacent to the key card inserting section 274, apanel 280 is disposed at the front end portion of the upper surface ofthe housing 4. Referring to FIG. 6, the panel 280 has arranged thereon apower switch 282, a print switch 284, a paper selection switch 286 andan interruption switch 288. When the power switch 282 is closed by amanual operation, the copying apparatus is connected to a suitable powersupply such as a commercial alternate-current power supply, and when thepower switch 282 is opened, the copying apparatus is cut off from thepower supply. When the print switch 284 is instantaneously closed by amanual operation, a signal for starting the copying process is produced.The paper selection switch 286 is maintained in one of two conditions.When it is maintained in one condition, the supply roller 64a in thepaper feed device 52 is set in an operable condition (therefore, acopying paper is ready for supplying from the paper cassette 58a loadedin the first cassette-receiving section 54a). When it is maintained inthe other condition, the supply roller 64b in the paper feed device 52is set in an operable condition (therefore, a copying paper is ready forsupplying from the paper cassette 58b loaded in the second cassettereceiving section 54b) (FIGS. 3 and 5). The interruption switch 288 ismanually closed when so-called "interrupting copying" is to beperformed, as will be described hereinafter. An operating knob 289 forcontrolling the amount of light exposure on the photosensitive member 20is also disposed on the panel 280. The panel 280 further includes teninput keys from 0 to 9 for inputting the number of copies to be producedfrom each document and a clear key 292 for cleaning the input numeralset by these input keys 290. The panel 280 further has a key card lamp294 for showing that the key card 276 has not been inserted into the keycard inserting section 274 and the copying process performancepermission signal has not yet been produced; a waiting display lamp 296for showing that the heat-fixing device 104 has not yet attained therequired temperature; a service man call lamp 298 showing that adisorder has occurred in a constituent element in the copying apparatusand a service man is required for inspection and repair; and a troublelamp 300 which shows that a trouble has occurred in the conveying of acopying paper in the main body 2 of the copying apparatus, a trouble hasoccurred in the conveying of a document in the semi-automatic documentsupplying and discharging device, or a trouble has occurred in thesorter 10. A first display means 302 and a second display means 304 arealso arranged on the panel 280. Each of the first display means 302 andthe second display means 304 has two light emitting segments having theshape of the arabic FIG. 8. The mode of display by the first and seconddisplay means 302 and 304 will be described in more detail hereinafter.

BASIC OPERATING PROCEDURE OF THE COPYING APPARATUS

The operations of the copying apparatus as described hereinabove iscontrolled by a processing means 306 including microprocessorsconstituting various control and discrimating means.

With reference to FIGS. 3 and 7, when the power switch 282 (FIG. 6) ismanually closed, power is applied to the copying apparatus, whereby awaiting flag 308 included in the processing means 306 is set at logic"1" and the electrical heating means 106 of the heating fixing device104 and the electrical heating means 273 (FIG. 4) for heating thephotosensitive member 20 are energized (the controlling of theenergization and deenergization of the heating means 106 and the heatingmeans 273 will be described in more detail hereinafter). When thewaiting flag 308 is set at logic "1", the waiting display lamp 296 (FIG.6) is energized to indicate that the copying apparatus is in apreparatory condition, and the copying apparatus is prevented fromperforming the copying process described below. When the temperature ofthe heat fixing device 104 detected by the temperature detecting means277 exceeds a predetermined value as a result of heating by the heatingmeans 106, the waiting flag 308 is reset at logic "0", and the waitingdisplay lamp (FIG. 6) is deenergized.

The operator manipulates ten input keys 290 to input the number ofcopies to be produced from the same document. As a result, a copy numbersetting counter 310 included in the processing means 306 is set at apredetermined number, whereby a continuity flag 312 included in theprocessing means 306 is set at logic "1". The logic "1" of thecontinuity flag 312 shows that the copying process should becontinuously performed. When the number of copies to be produced fromthe same document is only one, it is not necessary to operate the inputkeys 290. In this case, the continuity flag 312 is set at logic "1" whenthe operator instantaneously closes the print switch 284 (FIG. 6).

When the semi-automatic document supplying and discharging device 6 isnot utilized, a document is placed by hand on the transparent plate 12,and the document holding device 8 is brought to its operating position(the position shown in FIG. 2). Then, the operator instantaneouslycloses the print switch 284 (FIG. 6) by a manual operation, whereupon acopying process performance signal is produced. If at this time, aninhibition flag 314 included in the processing means 306 is not set atlogic "1" (the setting of the inhibiting flag 314 will be describedhereinafter) and therefore the copying process can be performed, therotation of the rotating drum 18 and the operation of the developingmeans 40 are started in response to the copying process performancesignal, and a copying paper is delivered from one of the paper cassettes58a and 58b in the paper feed device 52 (from which of the cassette 58aor 58b the paper is delivered depends upon the condition of the paperselection switch 286 described hereinabove). When the paper 56a isdelivered from the paper cassette 58a, the supply roller 64a is rotated.When the leading edge of the copying paper 56a delivered by the supplyroller 64a abuts against the nip position of the pair of stationaryconveyor rollers 84 and 86 and the copying paper 56a is bent as shown bythe two-dot chain line in FIG. 5, the detecting means 216 is closed tothereby stop the rotation of the supply roller 64a. When the copyingpaper 56b is delivered from the paper cassette 58b, the pair of supplyassisting rollers 80 and 82 are rotated together with the supply roller64b. When the leading edge of the copying paper 56b delivered by thesupply roller 64b is detected by the detecting means 228, a firstcounter 316 for paper conveyance included in the processing means 306starts to count clock pulses supplied from a clock pulse supply source318. When the counter 316 has counted a predetermined number, therotation of the supply roller 64b is stopped, and the delivered copyingpaper 56b is fed by the pair of supply assisting rollers 80 and 82. Theaforesaid predetermined number counted by the counter 316 is set at avalue corresponding to the time sufficient for the leading edge of thecopying paper 56b to reach the nip position of the pair of supplyassisting rollers 80 and 82. When the leading edge of the copying paper56b fed by the pair of supply assisting rollers 80 and 82 abuts againstthe nip position of the pair of stationary conveyor rollers 84 and 86and the copying paper 56b is bent as shown by the two-dot chain line inFIG. 5, the detecting means 216 is closed to thereby stop the rotationof the pair of supply assisting rollers 80 and 82.

When the above-described paper supplying action is terminated and thedetecting means 216 is closed, the counted numbers of a copying cyclecounter 320 and a copying paper counter 322 included in the processingmeans 306 are increased by one. When the countered number of the copyingcycle counter 320 becomes equal to that of the copy number settingcounter 310, the continuity flag 312 is reset at logic "0". The papercounter 322 will be described further hereinafter.

At the same time, when the copying process performance signal isproduced, the document illuminating lamp 118 is energized, and a timingcounter 324 included in the processing means 306 starts to count clockpulses supplied from the clock pulse supply source 318. When the counter324 has counted a first predetermined number, the supporting frames 130and 132 of the optical unit 116 begin to move to the right in FIG. 3from their initial positions shown by the solid line in FIG. 3.Thereafter, when the counter 324 has counted a second predeterminednumber, the charging corona discharge device 38 is energized. Thus, alatent electrostatic image is formed on the photosensitive member 20,and then developed into a toner image.

When the support frame 132 of the optical unit 116 has moved apredetermined distance l₃, the detecting means 254 detects it. As aresult, the pair of conveyor rollers 84 and 86 (and the pair of supplyassisting rollers 80 and 82) are rotated, and at the same time, the pairof conveyor rollers 92 and 94, the conveying belt mechanism 100 and therollers 108 and 110 of the heat-fixing device 104 are rotated. Thus, theconveying of the copying paper having its leading edge located at thenip position of the pair of conveyor rollers 84 and 86 is started.

When the detecting means 232 has detected the leading edge of thecopying paper, a first counter 326 for transfer included in theprocessing means begins to count clock pulses supplied from the clockpulse supply source 318. When the counter 362 has counted apredetermined number, the transfer corona discharge device 42 isenergized. Thus, the toner image on the photosensitive member 20 istransferred to the copying paper in the transfer zone. Thereafter, inthe peeling zone 32, the copying paper is peeled off from thephotosensitive member 20 by the action of the peeling corona dischargedevices 44 and 46. By the copying process performance signal, thepeeling corona discharge devices 44 and 46 begin to be energized as soonas the rotating drum 18 begins to rotate, and are deenergized when therotation of the rotating drum 18 is stopped after the termination of thecopying process.

When the copying paper is further conveyed, and the detecting means 232detects the passage of the trailing edge of the copying paper past thedetecting position of the detecting means 232, the charging coronadischarge device 38 and the document illuminating lamp 18 aredeenergized, and furthermore, the supporting frames 130 and 132 of theoptical unit 116 stop moving to the right in FIG. 3 and begin to move tothe left in FIG. 3. At the same time, a second counter 328 for transferincluded in the processing means 306 begins to count clock pulsessupplied from the clock pulse supply source 318. When the counter 328has counted a predetermined number, the transfer corona discharge device42 is deenergized.

The copying paper is further conveyed by the conveying belt mechanism100 and the rollers 108 and 110 of the heat fixing device 104, anddischarged into the sorter 10. When at this time, the continuity flag312 is set at logic "1", one bin 204 of the sorter 10 is moveddownwardly when a second paper conveyance counter 330, which begins tocount clock pulses supplied from the clock pulse supply source 318 whenthe trailing edge of the copying paper has gone past the deetectingposition of the detecting means 236, has counted a predetermined number.Simultaneously, the counted number of the paper counter 322 is decreasedby one.

When the support frames 130 and 132 of the optical unit 116 moving tothe left in FIG. 3 reach their initial positions shown by the solid linein FIG. 3, the detecting means 252 detects it. When the continuity flag312 is reset at logic "0", the support frames 130 and 132 of the opticalunit 116 are stopped at the initial positions. On the other hand, whenthe continuity flag 312 is set at logic "1", the support frames 130 and132 of the optical unit 116 begin to move to the right in FIG. 3 for thenext cycle of copying simultaneously with (or as will be describedbelow, after the lapse of a predetermined period of time from) thestopping of their leftward movement in FIG. 3. At this time, the paperdelivery action of the next copying cycle has already ended, and theleading edge of a copying paper for the next copying cycle stops inabutment against the nip position of the pair of stationary conveyorrollers 84 and 86. How the action of delivering paper for the nextcopying cycle is started will be described in detail hereinafter.

When the continuity flag 312 is set at logic "1", the rotating drum 18continues to rotate for the next copying cycle. But when the continuityflag 312 is reset at logic "0", the rotating drum 18 is stopped at asuitable time after it has undergone the cleaning action of the cleaningblade 48 or the cleaning action of the developing means 40 (this featurewill be described further hereinafter).

When the semi-automatic document supplying and discharging device 6 isutilized, the main frame structure 16 is brought to its operatingposition shown in FIGS. 1 and 3. The operator manually introduces adocument into the introducing portion 144 of the conveying passage 140.As a result, the detecting means 258 detects the inserted document toproduce a document insertion signal. When the document insertion signalis produced, the print switch 284 (FIG. 6) is instantaneously closed,and quite the same procedure as in the case of producing the aforesaidcopying process performance signal is performed in the main body 2 ofthe copying apparatus.

On the other hand, in the semi-automatic document supplying anddischarging device 6, the motor 188 is energized upon the production ofthe document insertion signal, thereby rotating the driven roller 164 ofthe conveying roller unit 160 and the conveying belt mechanism 170. Atthe same time, the solenoid 168 is energized to press the followerroller 166 of the conveying roller unit 160 against the driven roller164 and simultaneously cause the first regulating member 162 to moveaway from the introducing portion 144 thereby permitting advancing ofthe document. Thus, the inserted document is conveyed to the mainportion 142 from the introducing portion 144.

When the detecting means 258 has detected the passage of the trailingedge of the inserted document past the detecting position of thedetecting means 258, a first counter 332 for document conveyanceincluded in the processing means 306 begins to count clock pulsessupplied from the clock pulse supplying source 318. When the counter 332has counted a predetermined number, the solenoid 168 is deenergized.

When the detecting means 264 detects the leading edge of the documentconveyed by the conveying belt mechanism 170, the motor 188 isdeenergized. But the document further advances owing to inertia, andstops when its leading edge makes contact with the second regulatingmember 192. Thus, the document is positioned as required on thetransparent plate 12.

The motor 188 is energized when the detecting means 232 has detected thepassage of the trailing edge of the copying paper past the detectingposition of the detecting means 232 after the copying process isperformed in the main body 2 of the copying paper through apredetermined number of cycles and the continuity flag 312 is reset atlogic "0" (namely, when the exposure of the document in the final cycleof the copying process has ended). Simultaneously, the solenoid 196 isenergized to cause the second regulating member 192 to move away fromthe main portion 142, thereby permitting advancing of the document.Thus, the document is discharged by the conveying belt mechanism 170from the main portion 142 through the curved discharging portion 146.

When the detecting means 266 has detected the passage of the trailingedge of the document past the detecting position of the detecting means266, a second counter 334 for document conveyance included in theprocessing means 306 begins to count clock pulses supplied from theclock pulse supply source 318. When the counter 334 has counted apredetermined number, the motor 188 and the solenoid 196 aredeenergized.

When the next document has been introduced into the introducing portion144 by hand before the previous document is discharged from thetransparent plate 12, the aforesaid procedure is not immediatelyperformed even when the detecting means 258 has detected the documentand produced a document insertion signal. The aforesaid procedure isperformed when the previous document has been completely discharged(i.e., after the counter 334 has counted a predetermined number).

DETECTION OF TROUBLES IN THE CONVEYING OF THE COPYING PAPER AND THEDOCUMENT

In the main body 2 of the copying apparatus, conveying troubles such asjamming of the copying paper are detected in the following instances.

(1) When the delivery of a copying paper by the supply roller 64a or 64bis started, a first paper jam counter 336 included in the processingmeans 306 begins to count clock pulses supplied from the clock pulsesupply source 318, but the counter 336 has counted a predeterminednumber without being reset by the detection of the leading edge of thecopying paper by the detecting means 232.

(2) When the detecting means 232 has detected the leading edge of thecopying paper, a second paper jam counter 338 included in the processingmeans 306 begins to count clock pullses supplied from the clock pulsesupply source 318, but the counter has counted a predetermined numberwithout being reset by the detection of the leading edge of the copyingpaper by the detecting means 234.

(3) The detecting means 244 has detected the wrapping of the copyingpaper about the photosensitive member 20.

(4) The detecting means 244 has detected the wrapping of the copyingpaper about the photosensitive member 20 and the detecting means 234 hasdetected the copying paper (this means that two sheets of copying paperare delivered simultaneously, and one of them wraps about thephotosensitive member 20).

(5) When the detecting means 234 has detected the leading edge of thecopying paper, a third paper jam counter 340 included in the processingmeans 306 begins to count clock pulses supplied from the clock pulsesupply source 318, but the counter 340 has counted a predeterminednumber without being reset by the detection of the leading edge of thecopying paper by the detecting means 236.

(6) When the detecting means 236 has detected the leading edge of thecopying paper, a fourth paper jam counter 342 included in the processingmeans 306 begins to count clock pulses supplied from the clock pulsesupply source 318, but the counter 342 has counted a predeterminednumber without being reset by the detection of the trailing edge of thecopying paper by the detecting means 236.

In the semi-automatic document supplying and discharging device 6,jamming of a document is detected in the following instances.

(1) When the motor 188 is energized for supplying the inserted documentto the transparent plate 12, a first document jam counter 344 includedin the processing means 306 begins to count clock pulses supplied fromthe clock pulse supply source 318, but the counter 344 has counted apredetermined number without being reset by the detection of the leadingedge of the document by the detecting means 264.

(2) When the motor 188 is energized for discharging the document fromthe transparent plate 12, a second document jam counter 346 begins tocount clock pulses supplied from the clock pulse supply source 318, butthe counter 346 has counted a predetermined number without being resetby the detection of the leading edge of the document by the detectingmeans 266.

(3) When the detecting means 266 has detected the leading edge of thedocument, a third document jam counter 348 included in the processingmeans 306 begins to count clock pulses supplied from the clock pulsesupply source 318, but the counter 348 has counted a predeterminednumber without being reset by the detection of the trailing edge of thedocument by the detecting means 266.

CONTROL OF THE POSITIONING OF THE CLEANING BLADE

As already stated with reference to FIGS. 3 and 4, in the main body 2 ofthe copying apparatus, a cleaning blade 48 made of a suitable flexiblematerial such as synthetic rubber is disposed for removing the residualtoner from the photosensitive member 20 in the cleaning zone 34 locatedaround the rotating drum 18. The cleaning blade 48 is supported by ablade supporting mechanism 354 known per se including a solenoid 352 asillustrated in a simplified form in FIG. 4. When the solenoid 352 isenergized, the cleaning blade 48 is held at its operating position shownby the solid line in FIG. 4. When it is deenergized, it is held at itsnon-operating position shown by the two-dot chain line in FIG. 4. At theoperating position shown by the solid line in FIG. 4, the cleaning blade48 is pressed elastically against the photosensitive member 20 on therotating drum 18. On the other hand, at the non-operating position shownby the two-dot chain line in FIG. 4, the cleaning blade 48 is away fromthe photosensitive member 20 on the rotating drum 18.

As already stated hereinabove, a magnetic brush type developing means 40is disposed in the developing zone 28 around the rotating drum 18 in themain body 2 of the copying apparatus. As is well known to those skilledin the art, the magnetic brush-type developing means 40 can be used notonly for developing a latent electrostatic image formed on thephotosensitive member 20 but also, as a cleaning means, for removing theresidual toner from the photosensitive member 20 after the transfer.When the magnetic brush-type developing means 40 is used as a cleaningmeans, the rotating drum 18 should additionally be kept rotating evenafter the transfer so that that area of the photosensitive member onwhich the toner remains after the transfer (i.e., that area where thetoner image is formed) passes through the developing zone 28 and thusundergoes the cleaning action of the magnetic brush-type developingmeans 40; and then the next cycle of the copying process should bestarted. Hence, the copying time necessarily becomes longer.

It will be easily understood on the other hand that when the residualtoner on the photosensitive member 20 is removed by using the cleaningblade 48, it is not necessary to keep the rotating drum 18 rotatingadditionally, and therefore, the time required for copying can beminimized. In the case of removing the residual toner from thephotosensitive member 20 by means of the cleaning blade 48, thephotosensitive member and/or the cleaning blade 48 tends to be degradedrelatively early because the cleaning blade 48 is pressed against thephotosensitive member 20.

In the main body 2 of the copying apparatus, paper cassettes containingcopying paper sheets of various sizes are selectively mounted on thefirst cassette receiving section 54a and the second cassette receivingsection 54b of the paper feeding device 52, and copying paper sheets ofvarious sizes are selectively delivered and conveyed through thetransfer zone 30. Some of these sizes are longer than the total lengthof the photosensitive member 20, and the others are equal to, or smallerthan, the photosensitive member 20. As will be understood from theforegoing description about the basic operating procedure of the copyingapparatus, the length of a toner image formed on the photosensitivemember 20 is substantially equal to the length of a copying paperdelivered.

In view of the aforesaid fact, in the copying apparatus improved inaccordance with this invention, when a copying paper conveyed throughthe transfer zone 30 is a long one having a length larger than the totallength of the photosensitive member 20, the cleaning blade 48 ispositioned at the aforesaid operating position and thus performs itscleaning action. When a copying paper conveyed through the transfer zone30 is a short one having a length equal to, or smaller than, the totallength of the photosensitive member 20, the cleaning blade 48 is held atits non-operating position, and the magnetic brush-type developing means40 performs a cleaning action.

In the copying apparatus improved in accordance with this invention,when the copying paper conveyed through the transfer zone 30 is a shortone the cleaning blade 48 is held at its non-operating position and isaway from the photosensitive member 20. Hence, the life of thephotosensitive member 20 and/or the cleaning blade 48 becomescorrespondingly longer. When the copying paper conveyed through thetransfer zone 30 is a long one, the cleaning of the residual toner iscarried out by utilizing the magnetic brush-type developing means 40. Itis necessary therefore to rotate the rotating drum 18 additionally afterthe transfer, and the copying time becomes correspondingly longer.However, as will be understood from the foregoing description of thebasic operating procedure of the copying apparatus, when the copyingpaper conveyed through the transfer zone 30 is a long one, the basiccopying time, i.e., the time other than the time during which therotating drum 18 is additionally rotated is relatively short. Hence, theprolongation of the copying time owing to the additional rotation of therotating drum 18 does not give rise to any practical problem.

With reference to FIG. 8 showing a flow chart of controlling ofpositioning of the cleaning blade 48 by the processing means 306 takenin conjunction with FIGS. 3, 4 and 7, it is judged in step n1-1 whetherthe aforesaid copying process performance signal has been produced bythe instantaneous closing of the print switch 284 (FIG. 6), or theaforesaid document insertion signal has been produced by the detectionof the inserted document by the detecting means 258. Then, step n1-2sets in. When the aforesaid copying process performance signal or thedocument insertion signal which induces the start of rotation of therotating drum 18 is produced, it is judged in step n1-2 whether thecopying paper to be delivered is a long paper, namely whether the lengthof the copying paper delivered is longer than the total length of thephotosensitive member 20. This judgement is made by (a) determining inwhich of the two conditions the paper selection switch 286 (FIG. 6) is(therefore which of the supply roller 64a and the supply roller 64b isactuated), and at the same time, (b) recognizing the paper cassette 58aloaded in the first cassette receiving section 54a on the basis of asignal from the discriminating means 208a, or recognizing the papercassette 58b loaded in the second cassette receiving section 54a on thebasis of a signal from the discriminating means 208. When the copyingpaper delivered is a long one, step n1-3 sets in. In step n1-3, thesolenoid 352 is energized, and consequently, the cleaning blade 48 isheld at its operating position shown by the solid line in FIG. 4. Then,in step n1-4, the copying process described hereinabove is performed.When in step n1-2, the delivered copying paper is a short one, step n1-4sets in subsequent to step n1-2, and therefore, the solenoid 352 ismaintained in the deenergized state and the cleaning blade 48 is held atits non-operating position shown by the two-dot chain line in FIG. 4. Instep n1-5, it is judged whether the transfer corona discharge device 42has been deenergized as above. When the transfer corona discharge device42 is deenergized, step n1-6 sets in. In step n1-6, it is judged whetherthe continuity flag 312 is set at logic "1" and therefore the next cycleof the copying process is successively carried out. When the continuityflag 312 is set at logic "1", step n1-7 sets in. In step n1-7, it isagain judged whether the copying paper is a long paper or not. When thecopying paper is a long one, step n1-4 again sets in. When the copyingpaper is a short one, step n1-8 sets in. In step n1-8, a cleaningcounter 356 included in the processing means 306 begins to count clockpulses supplied from the clock pulse supply source 318. In step n1-9, itis judged whether the cleaning counter 356 has counted a predeterminednumber. After the cleaning ounter 356 has counted the predeterminednumber, step n1-4 again sets in. Before the cleaning counter 356 hascounted the predetermined number, the rotating drum 18 keeps rotatingwhile the charging corona discharge device 38 and the transfer coronadischarge device 42 are in the deenergized state. During this time, themagnetic brush-type developing means 40 removes a toner remaining on thephotosensitive member 20 after the transfer. The aforesaid predeterminednumber of the cleaing counter 356 is set such that the time from thebeginning of counting by the cleaning counter 356 becomes equal to thetime required for the rotating drum 18 to rotate through at least oneturn after the rear edge of that area of the photosensitive member 20 inwhich the toner image is formed, i.e. that area of the photosensitivemember 20 with which the copying paper is brought into contact in thetransfer zone, has gone past the developing zone 28. When it isdetermined in step n1-6 that the continuity flag 312 is reset at logic"0", step n1-6 is followed by step n1-10 in which the cleaning counter356 begins counting. In step n1-11, it is judged whether the cleaningcounter 356 has counted a predetermined number (this predeterminednumber may be equal to, or larger than, the predetermined number in stepn1-9). During the time from the starting of counting by the cleaningcounter 356 to the counting of the aforesaid predetermined number, therotating drum 18 keeps rotating while the charging corona dischargedevice 38 and the transfer corona discharge device 42 are maintained inthe deenergized state. During this time, the residual toner is removedfrom the photosensitive member 20 by the cleaning bladed 48 (in the caseof a long copying paper) or the magnetic brush-type developing means 40(in the case of a short copying paper). When the cleaning counter hascounted the predetermined number, step n1-12 sets in. In step n1-12, thesolenoid 352 is deenergized if it is in the energized state.Furthermore, in step n1-13, the rotation of the rotating drum 18 isstopped.

CONTROL OF CONTINUED DELIVERY OF THE COPYING PAPER

With reference to FIGS. 3 and 5, in the copying apparatus describedhereinabove, when the next cycle of the copying process is performedsuccessively after the previous copying cycle, it is desired to startdelivery of a copying paper for the next copying cycle as early aspossible after the paper delivery in the previous copying cycle. On theother hand, the delivery of a copying paper in the next cycle of copyingshould be started (a) in order to prevent overlapping of the trailingedge portion of the copying paper fed in the previous copying cycle withthe leading edge of the copying paper delivered fed in the next cycle ofcopying in the first paper introducing passage 70a or the second paperintroducing passage 70b, after the copying paper delivered in theprevious copying cycle and abutting at its leading edge against the nipposition of the pair of stationary conveyor rollers 84 and 86 begins tobe conveyed by the pair of conveyor rollers 84 and 86 whose rotation hasbeen started, and (b) after the trailing edge of the copying paperdelivered in the previous copying cycle has departed from the papercassette 58a or 58b. As stated hereinabove, various paper cassettes areselectively mounted on the first and second cassette receiving sections54a and 54b, and the length of a copying paper to be delivered isvarious. When a copying paper of a relatively large length is delivered,the trailing edge of the copying paper departs from the paper cassetteonly after the lapse of a relatively long period of time from thestarting of conveying of the delivered paper by the pair of conveyorrollers 84 and 86. When a relatively short copying paper is delivered,the trailing edge of the copying paper departs from the paper cassetteafter the lapse of a relatively short period of time from the startingof the conveying of the delivered copying paper by the pair of conveyorrollers 84 and 86. When a copying paper is to be delivered from thepaper cassette 58b loaded in the second cassette receiving section 54b,the length of the copying paper may sometimes be shorter than the lengthof the second paper introducing passage 70b extending from the papercassette 58b to the pair of conveyor rollers 84 and 86. Hence, itsometimes happens that when the leading edge of the delivered copyingpaper has arrived at the nipping position of the conveyor rollers 84 and86, the trailing edge of the copying paper has already departed from thepaper cassette 58b.

In conventional copying apparatuses, the starting of delivery of acopying paper in the next copying cycle is controlled on the basis ofthe longest copying paper in order to meet the requirements (a) and (b)described above. Specifically, the delivery of a copying paper in thenext copying cycle is started after a period of time required for thetrailing edge of the longest copying paper to depart from the papercassette or a longer period of time after the initiation of rotation ofthe pair of conveyor rollers 84 and 86 and therefore the initiation ofconveying of the previous copying paper. Such a conventional copyingapparatus suffers from the inconvenience that if the copying paper to bedelivered is relatively short, the starting of delivery of the copyingpaper in the next copying cycle becomes undesirably slow. It isimportant that the leading edge of the copying paper in the next copyingcycle should reach the nip position of the pair of conveyor rollers 84and 86 before the support frames 132 (and 130) of the optical unit 116,which have moved to the right in FIG. 3 and then to the left in FIG. 3in the previous copying cycle and thus have returned to their initialpositions, again begin to move to the right in FIG. 3 for the next cycleof copying and have advanced over the predetermined distance l₃.Otherwise, it would be impossible to perform the scanning exposure ofthe document and the conveyance of the copying paper in synchronism. Incontrast, when the copying paper is relatively short, the reciprocatingdistance of the support frame 132 of the optical unit 116 in theprevious copying cycle is relatively short, and therefore, the supportframe 132 returns to its initial position relatively early. Hence, whenthe reciprocal movement of the support frame 132 is started for the nextcopying cycle simultaneously with or immediately after the returning ofthe support frame 132 to its initial position, the copying paperdelivered in the next copying cycle does not reach the nip position ofthe pair of conveying rollers 84 and 86 before the support frame 132moves the predetermined distance l₃. To avoid the occurrence of such asituation, the starting of the reciprocation of the support frame 132 inthe next copying cycle should be delayed, and consequently, the copyingtime becomes longer than necessary.

In the copying apparatus of this invention, the following improvementhas been made in order to avoid the aforesaid disadvantage of theconventional copying apparatus.

With reference to FIG. 9 showing a flow chart of controlling thedelivery of a copying paper by the processing means 306 taken inconjunction with FIG. 5, it is judged in step n2-1 whether the aforesaidcopying process performance signal has been produced by theinstantaneous closing of the print switch 284 (FIG. 6), or whether theaforesaid document insertion singal has been produced by the detectionof the inserted document by the detecting means 258. When the aforesaidcopying process performance signal or the document insertion signal hasbeen produced, step n2-2 sets in. In step n2-2, it is judged whether thepaper selection switch 286 is in a first or a second condition. When thepaper selection switch 286 is in the first condition, step n2-3 sets in,and the supply roller 64a is rotated and the delivery of a copying paperfrom the paper cassette 58a is started. Then, in step n2-4, it is judgedwhether the detecting means 216 is closed or not. When the detectingmeans 216 is closed, step n2-5 sets in, and the rotation of the supplyroller 64a is stopped. Then, step n2-6 sets in and in this step, it isjudged whether the detecting means 254 (FIG. 3) has been closed as aresult of detecting the support frame 132 of the optical unit 116. Whenthe detecting means 254 is closed, step n2-7 sets in, and the pair ofconveyor rollers 84 and 86 are rotated to start the conveying of thecopying paper. Then, step n2-8 sets in, and it is judged whether thecontinuity flag 312 is set at logic "1". In other words, it is judgedwhether the copying process is to be performed further. When thecontinuity flag 312 is set at logic "1", step n2-9 sets in, and it isjudged whether the detecting means 232 has been closed as a result ofdetecting the leading edge of the copying paper. When the detectingmeans 232 is closed, step n2-10 sets in. In step n2-10, it is judgedwhether the shaft 62a having the supply roller 64a fixed thereto isrotating. Such a judgement is made by determining whether the lightreceiving element of the detecting means 210a alternately assumes acondition in which it does not receive light and a condition in which itreceives light and therefore the production and dispearance of a signalare alternately repeated (when the shaft 62a is rotating), or the lightreceiving element of the detecting means 21a is continuously maintainedin a condition in which it does not receive light or, a condition inwhich it receives light and therefore the production or disappearance ofa signal is continuously maintained (when the shaft 62a is at rest).When the trailing edge portion of the copying paper which has begun tobe conveyed by the pair of conveyor rollers 84 and 86 is still incontact with the supply roller 64a, the supply roller 64a and the shaft62a are rotated following the movement of the trailing edge of thecopying paper being conveyed [the shaft 62a having the supply roller 64afixed thereto is connected to a drive source by a suitable clutch means(not shown) such as an electromagnetic clutch when it is rotated, butwhen the clutch means is in an inoperative condition and cut off fromthe drive source, the shaft 62a can freely rotate at least in thedelivery direction, i.e. in the clockwise direction in FIG. 5]. However,when the trailing edge of the copying paper being conveyed leaves thesupply roller 64a, the rotation of the supply roller 64a and the shaft62a comes to a stop. When the rotation of the shaft 62a stops, stepn2-11 sets in, and a delivery counter 358 included in the processingmeans 306 begins to count clock pulses supplied from the clock pulsesupply source 318. Thereafter, in step n2-12, it is judged whether thedelivery counter 358 has counted a predetermined number. When thedelivery counter 358 has counted the predetermined number, step n2-2again sets in, and the delivery of a copying paper for the next copyingcycle is started. The above predetermined number of the delivery counter358 is set such that the time required for the counter 358 to count thepredetermined number after the starting of counting is substantiallyequal to, or slightly longer than, the time required for the trailingedge of the copying paper to leave the paper cassette 58a after leavingthe supply roller 64a.

On the other hand, when in step n2-2 the paper selection switch 286 isin the second condition, n2-13 sets in, and the supply roller 64b andthe pair of supply assisting rollers 80 and 82 are rotated, and thedelivery of a copying paper from the paper cassette 58b is started.Then, in step n2-14, it is judged whether the detecting means 228 hasbeen closed as a result of detecting the leading edge of the copyingpaper. When the detecting means 228 is closed, step n2-15 sets in. Instep n2-15, the first paper conveyance counter 316 begins to count clockpulses supplied from the clock pulse supply source 318. Then, it isjudged in step n2-16 whether the counter 316 has counted a predeterminednumber. When the counter 316 has counted the predetermined number, stepn2-17 sets in and the rotation of the supply roller 64b is stopped (butthe delivery roller 64b is kept rotating incident to the movement of thecopying paper being conveyed). Thereafter, it is judged in step n2-18whether the detecting means 216 is closed. When the detecting means 216is closed, step n2-19 sets in, and the rotation of the pair of supplyassisting rollers 80 and 82 is stopped. Step n2-20 then sets in, and itis judged whether the detecting means 254 (FIG. 3) has been closed as aresult of detecting the support frame 132 of the optical unit 116. Whenthe detecting means 254 is closed, step n2-21 sets in, and the pair ofconveyor rollers 84 and 86 are rotated and simultaneously the pair ofsupply assisting rollers 80 and 82 are rotated. Thus, the conveyance ofthe copying paper is started. Then, step n2-22 sets in, and it is judgedwhether the continuity flag 312 is set at logic "1". When the continuityflag 312 is set at logic "1", step 2-23 sets in, and it is judgedwhether the detecting means 232 has been closed as a result of detectingthe leading edge of the copying paper. When the detecting means 232 isclosed, step n2-24 sets in. In step n2-24, it is judged whether theshaft 62b having the supply roller 64b fixed thereto is rotating. Such ajudgement is made on the basis of a signal from the detecting means 210bas is the case with the judgement in step n2-10. When the rotation ofthe shaft 62b is stopped, step n2-25 sets in, and the delivery counter358 begins to count clock pulses supplied from the clock pulse supplysource 318. Then, in step n2-26, it is judged whether the deliverycounter 358 has counted a predetermined number. This predeterminednumber may be the same as the predetermined number in step n2-12. Whenthe delivery counter 358 has counted the predetermined number, step n2-2again sets in, and the delivery of the copying paper for the nextcopying cycle is started.

According to the above-described control of continued delivery of acopying paper, when the requirements (a) and (b) for starting thedelivery of the next copying paper are met, the delivery of the nextcopying paper is started without any substantial delay irrespective ofthe length of the copying paper. Thus, the aforesaid disadvantage in theconventional copying apparatus can be avoided.

In the illustrated embodiment, the departing of the copying paper fromthe paper cassette 58a or 58b is detected by utilizing the detectingmeans 210a and 210b for detecting the stopping of the rotation of theshafts 62a and 62b having the supply rollers 64a and 64b fixed theretoand the delivery counter 358 associated with the detecting means 210aand 210b. If desired, instead of this, the departing of the copyingpaper from the paper cassette 58a or 58b can be detected by providing asuitable paper detecting means capable of detecting a copying paperimmediately below the paper cassette 58a or 58b and detecting thepassing of the trailing edge of the copying paper past the detectingposition of such detecting means.

CONTROL OF INTERRUPTING COPYING

When the semi-automatic document supplying and discharging device 6 isnot used, so-called "interrupting copying" is possible without anyprobem in conventional apparatuses, too. No technique, however, has beenestablished to date which makes interrupting copying possible withoutany problem even when the semi-automatic document supplying anddischarging device 6 is used. In contrast, in the copying apparatusimproved in accordance with this invention, interrupting copying can beperformed without any problem even in the case of using thesemi-automatic document supplying and discharging device 6.

This improvement achieved by this invention will be described withreference to FIG. 10 showing a flow chart of controlling thesemi-automatic document supplying and discharging device 6 by theprocessing means 306 taken in conjunction with FIGS. 3 and 7. In stepn3-1, it is judged whether the detecting means 258 has produced adocument insertion signal by detecting a document inserted into thedocument inserting portion. When the document insertion signal has beenproduced, the rotation of the rotating drum 18 and the delivery of acopying paper are started in the main body 2 of the copying apparatus asalready stated. When the detecting means 216 has been closed by thedelivered copying paper, the counted number of the copying processcounter 320 included in the processing means 306 is increased by one. Onthe other hand, as regards the semi-automatic document supplying anddischarging device 6, step n3-2 sets in when the document insertionsignal is produced. As a result, the motor 188 and the solenoid 168 areenergized to start conveying of the inserted document. Then, in stepn3-3, it is judged whether the document insertion signal has disappearedas a result of the passage of the trailing edge of the document past thedetecting position of the detecting means 258. When the documentinsertion signal disappears, step n3-4 sets in, and the first counter332 for document conveyance begins to count clock pulses supplied fromthe clock pulse supply source 318. In step n3-5, it is judged whetherthe counter 332 has counted a predetermined number. When the counter 332has counted the predetermined number, step n3-6 sets in, and thesolenoid 168 is deenergized. Then, in step n3-7, it is judged whetherthe detecting means 264 has been closed as a result of detecting theleading edge of the document. When the detecting means 264 is closed,step n3-8 sets in, and the motor 188 is deenergized. Thus, as statedhereinabove, the document is positioned as required on the transparentplate 12. Then, in step n3-9, it is judged which of an interruptingsignal (logic "1") or a non-interrupting signal (logic "2") the signalproducing means 360 (FIG. 7) is producing in response to the operationof the interruption switch 288. When the operator has no intention ofperforming interrupting copying, and therefore a non-interupting signalis produced, step n3-10 sets in. In step n3-10, it is judged whether thecontinuity flag 312 is reset at logic "0". Step n3-11 sets in when thecounted number of the copying process counter 320 which is increased oneby one every time the delivery of the copying paper is performed in themain body 2 of the copying paper (and therefore, every time the copyingcycle is performed) becomes equal to the counted number of the copynumber counter 310 set by the operator, and therefore, the copyingprocess is performed through the desired number of cycles and thecontinuity flag 312 is reset at logic "0". In step n3-11, it is judgedwhether the detecting means 232 has detected the passing of the trailingedge of the copying paper past the detecting position of the detectingmeans 232, namely whether exposure in the final copying cycle has ended.When the exposure has ended, step n3-12 sets in, and the motor 188 andthe solenoid 196 are energized. As a result, the discharging of thedocument from the transparent plate 12 is started. Thereafter, in stepn3-13, it is judged whether the detecting means 266 once closed has beenopened as a result of its detection of the passage of the trailing edgeof the document past the detecting position of the detecting means 266.When the detecting means 266 is opened, step n3-13' sets in, andsolenoid 196 is energized. Thereafter, step n3-14 sets in, and it isjudged whether the detecting means 258 has produced a document insertionsignal as a result of its detection of the insertion of the nextdocument. When no document insertion signal is produced, step n3-15 setsin, and the motor 188 is deenergized. When the document insertion signalis produced, step n3-2 again sets in, and the conveying of the nextdocument is started.

On the other hand, when the operator intends to perform interruptingcopying and operates the interruption switch 288 (FIG. 6), the signalproducing means 360 (FIG. 7) produces an interrupting signal. When thesignal interrupting signal is produced, the addition of a count numberto the copying process counter 320 is inhibited, even if the delivery ofa copying paper is performed in the main body 2 of the copying apparatusand the detecting means 216 is closed. Step n3-9 is thus followed bystep n3-16. In step n3-16, it is judged whether the detecting means 232has detected the passage of the trailing edge of the copying paper pastthe detecting position of the detecting means 232, namely whetherexposure in the copying process at the time of producing theinterrupting signal has ended. When the exposure comes to an end, stepsn3-17, n3-18 and n3-19 which are the same as the steps n3-12, n3-13 andn3-15 are performed, and thus, the document located on the transparentplate 12 at the time of producing the interrupting signal is discharged.Then, step n3-20 sets in, and it is judged whether a document insertionsignal has been produced as a result of the insertion of a document forinterrupting copying before the discharging of the aforesaid document.When the document insertion signal is produced, step n3-21 sets in, andthe print switch 284 is manually closed and step n3-23 sets in. This isfor the purpose of making the operator fully aware that it is theperformance of interrupting copying. If desired, in step n3-21, it ispossible to energize a suitable display lamp or the like so as to urgethe operator to close the print switch 284 by hand. On the other hand,when no document insertion signal is produced in the step n3-20, stepn3-22 sets in, and it is judged whether a document insertion signal hasbeen produced as a result of the insertion of a document after thedischarging of the aforesaid document. When the document insertionsignal is produced, the aforesaid step n3-23 sets in. In this step n3-23and the following steps n3-24, n3-25, n3-26, n3-27, n3-28 and n3-29, thesame processings as in steps n3-2, n3-3, n3-4, n3-5, n3-6, n3-7 and n3-8are carried out. As a result, the document for interrupting copying ispositioned as required on the transparent plate 12. On the other hand,in the main body 2 of the copying machine, in step n3-20, the startingof the rotation of the rotating drum 18 and the delivery of a copyingpaper are inhibited, and the rotation of the rotating drum 18 and thedelivery of the copying paper are started for the first time in stepn3-23. Step n3-29 is followed by step n3-20. In step n3-20, it is judgedwhether the detecting means 232 has detected the passage of the trailingedge of the copying paper past the detecting position of the detectingmeans 232, namely whether exposure in the interrupting copying processhas ended. When the exposure comes to an end, step n3-31 sets in, and itis judged whether an interrupting signal has been produced. When theinterrupting signal is produced, steps n3-32, n3-33, n3-33', n3-34 andn3-35 which are the same as the above steps n3-12, n3-13, n3-13', n3-14and n3-15 are performed, and the document for interrupting copying isdischarged from the transparent plate 12. When the step n3-34, adocument insertion signal is produced as a result of the insertion ofthe next document for interrupting copying, step n3-23 again sets in. Instep n3-36 following step n3-35, it is judged whether an interruptingsignal has been produced. When the interrupting signal is produced, stepn3-22 again sets in. On the other hand, when the operator has endedinterrupting copying and operated the interruption switch 288 (FIG. 6)in order to return to ordinary copying whereby the signal producingmeans 360 (FIG. 7) produces a non-interrupting signal, step n-3-36 isfollowed by step n3-1. Thus, when the document used before theinterrupting copying is inserted by hand, it is supplied to thetransparent plate 12, and the copying process is performed through theremaining number of cycles for this document.

On the other hand, when the operator operates the interruption switch288 (FIG. 6) before the step n3-31 whereby the signal producing means360 (FIG. 7) produces a non-interrupting signal, the step n3-31 isfollowed by step n3-37. In step n3-37 and the following steps n3-38,n3-38', n3-39 and n3-40, the same processings as in steps n3-12, n3-13,n3-13', n3-14 and n3-15 are carried out, and the document forinterrupting copying is discharged from the transparent plate 12. Whenin step n3-39, a document insertion signal is produced as a result ofthe insertion by hand of the document before interrupting copying, theabove step n3-2 again sets in. Thus, the document used before theinterrupting copying is delivered to the transparent plate 12, and thecopying process is automatically repeated for this document through theremaining number of cycles.

TROUBLESHOOTING AND DISPLAY

This subject will be described with reference to FIGS. 11-A to 11-Dwhich are flow charts showing the controlling of the processing means306 relating to troubles taken in conjunction with FIGS. 3 and 7. Instep n4-1, it is judged whether a trouble has occurred in variousconstituent elements of the copying apparatus (for example, the documentilluminating lamp 118, the electrical heating means 106 of the heatfixing device 104, the electrical heating element 273 for heating thephotosensitive member 20, the temperature detecting means 277 fordetecting the temperature of the heat fixing device 104, and thedetecting means 279 for detecting the temperature of the surface or itsvicinity of the photosensitive member 20). When a trouble such as wirebreaks has occurred in the temperature detecting means 277 and thetemperature detecting means 279, detecting devices 281 and 283respectively supply trouble imdicating signals to the processing means306 (this will be further described hereinafter). Furthermore, when atrouble has occurred in other constituent elements, the detecting means275 supplys a trouble indicating signal to the processing means 306.When a trouble has occurred in the constituent elements in step n4-1,the details of the trouble (i.e., which of the constituent elements getsout of order) are stored in a trouble memory 362, and thereafter in stepn4-3, the inhibition flag 314 is set at logic "1" (hence, the operationof the copying machine is stopped). Thereafter, step n4-66 sets in.

When it is judged in step n4-1 that no trouble has occurred in theconstituent elements, step n4-4 sets in. In step n4-4, it is jedgedwhether the key card 276 is inserted in the key card inserting section274 (FIGS. 1 and 2) (i.e. whether the signal producing means 278 hasproduced a copying process performance permission signal). When the keycard 276 is not inserted, the fact that the key card 276 is not insertedis stored in a key card memory 364 included in the processing means 306in step n4-5, and thereafter in step n4-6, the inhibition flag 314 isset at logic "1". Then, step n4-66 sets in.

When the key card 276 is inserted in step n4-4, step n4-7 sets in, andin step n4-7 it is judged whether the first document jam counter 344 isset (namely, whether it is in condition for counting). When the counter344 is set, the counter 344 performs counting in step n4-8 andthereafter in step 4-9, it is judged whether the counter 344 has counteda predetermined number. When the counter 344 has counted thepredetermined number (namely when a document inserted by hand in thesemi-automatic document supplying and discharging device 6 has jammedduring its feeding to the transparent plate 12), the fact that thedocument jammed during feeding is stored in a document trouble memory366 included in the processing means 306 in step n4-10. In step n4-11,the continuity flag 312 is reset at logic "0", and in step n4-12, thecounted number of the copying process counter 320 is reduced to zero.Thereafter, in step n4-13, the inhibition flag 314 is set at logic "1".Then, step n4-66 sets in.

The following fact must be noted with regard to the step n4-12. When thedetecting means 258 detects the document inserted by hand in thesemi-automatic document supplying and discharging device 6, thesupplying of the document toward the transparent plate 12 is started,and simultaneously, the paper feeding operation of the paper feed device52 is started in the main body 2 of the copying apparatus. When thedetecting means 216 is closed by the copying paper supplied, the countednumber of the copying process counter 310 for indicating the number ofcopying cycles performed in the main body 2 of the copying apparatus isincreased by one. This increment in the copying process counter 310 isachieved before the counter 344 has counted the predetermined number.Accordingly, when the document inserted by hand in the semi-automaticdocument supplying and discharging device 6 jams during supplying to thetransparent plate, the counted value of the copying process counter 310becomes zero in spite of the fact that no copy is obtained because ofdocument jamming. Accordingly, in the copying apparatus improved inaccordance with this invention, the counted number of the copyingprocess counter 320 is brought to zero in step n4-12, and thus theoccurrence of the above inconvenience is avoided.

When the counter 344 is not set in step n4-7, and when the counter 344has not counted the predetermined number in step n4-9, step n4-14 setsin. In step n4-14, it is judged whether the first copying paper jamcounter 336 is set. When the counter 336 is set, the counter 364performs counting in step n4-15, and thereafter in step n4-16, it isjudged whether the counter 336 has counted a predetermined number. Whenthe counter 336 has counted the predetermined number (namely, when thecopying paper jams upstream of the detecting means 232), the fact thatthe copying paper jammed upstream of the detecting means 232 is storedin a paper trouble memory 368 included in the processing means 306 instep n4-17. Then, in step n4-18, the continuity flag 312 is reset atlogic "0", and thereafter in step n4-19, it is judged whether thecounted value of the copying paper counter 322 is 2 or more. If thecounted number of the paper counter 322 is not 2 or more, step n4-20sets in. In step n4-20, the inhibition flag 314 is set at logic "1", andthereafter, step n4-66 sets in. When the counted value of the papercounter 322 is 2 or more, after the delay of a predetermined period oftime in step n4-21, the inhibition flag 314 is set at logic "1" in stepn4-22. Then, step n4-66 sets in.

With regard to these steps n4-19 to n4-22, the following fact should benoted. As stated hereinabove, the paper counter 322 counts up by one asa result of the closing of the detecting means 216 by the copying paperfed to the first or second paper instroducing passage 70a or 70b fromthe paper feed device 52, and counts down by one when the trailing edgeof the copying paper has passed the detecting position of the detectingmeans 236 disposed at the discharge end portion of the paper conveyingpassage (in more detail, after the lapse of a predetermined period oftime defined by the predetermined number of the second paper conveyancecounter 330 from the aforesaid time of passage). Accordingly, thecounted number of the paper counter 322 indicates the number of copyingpaper sheets present in the first paper introducing passage 70a, thesecond paper introducing passage 70b and the paper conveying passage.The fact that the counted value of the paper counter 322 is 1 or 0 whenthe copying paper jams upwardly of the detecting means 232 means that nocopying paper exists downstream of the detecting means 232. In such acase, the inhibition flag 314 is set at logic "1" in step n4-20 to stopthe operation of the copying apparatus immediately. On the other hand,the fact that the counted value of the paper counter 322 is 2 or morewhen the copying paper jams upstream of the detecting means 232 meansthat a separate copying paper different from the jamming paper existsdownstream of the detecting means 232. In such a case, a delay of apredetermined period of time is provided in step n4-21 to continue theoperation of the copying apparatus for a required period of time, andthe separate copying paper existing downstream of the detecting means232 is discharged into the sorter 10. Thereafter, in step n4-22, theinhibition flag 314 is set at logic "1" to stop the operation of thecopying apparatus.

When the counter 336 is not set in step n4-14, and when the counter 336has not counted the predetermined value, step n4-23 sets in, and in stepn4-23, it is judged whether the second paper jam counter 338 is set.When the counter 338 is set, the counter 338 performs counting in stepn4-24, and thereafter, in step n4-25 it is jedged whether the counter338 has counted a predetermined number. When the counter 338 has countedthe predetermined number (namely, when the copying paper jams in a pathfrom the detecting means 232 to the detecting means 234 and/or thecopying paper wraps about the photosensitive member 20), step n4-26 setsin. In step n4-26, it is judged whether the detecting means 244 detectsthe copying paper. When the detecting means 244 detects the copyingpaper (namely, when the counting of the predetermined number by thecounter 338 in step n4-25 is attributed to the wrapping of the copyingpaper about the photosensitive member 20), the wrapping of the paperabout the photosensitive member 20 is stored in the paper trouble memory368 in step n4-27, and in step n4-28, the continuity flag 312 is resetat logic "0". Thereafter, in step n4-29, the inhibition flag 314 is setat logic "1", and then step n4-66 sets in. When the detecting means 244does not detect the copying paper in step n4-26 (namely, when thecounting of the predetermined number by the counter 338 in step n4-25 isattributed to the jamming of the copying paper in a path from thedetecting means 232 to the detecting means 234), the jamming of thecopying paper between the detecting means 232 and the detecting means234 is stored in the paper trouble memory 368 in step n4-30, and in stepn4-31, the continuity flag 312 is reset at logic "0". Thereafter, instep n4-32, the inhibition flag 314 is set at logic "1", and then stepn4-66 sets in.

When the counter has not counted the predetermined number in step n4-25,step n4-33 sets in. In step n4-33, it is judged whether the detectingmeans 244 detects the copying paper. The detection of the copying paperby the detecting means 244 in step n4-33 means that the detecting means244 has detected the wrapping of the copying paper about thephotosensitive member in spite of the fact that because of the detectionof the copying paper by the detecting means 234, the counter 338 has notcounted the predetermined number in step n4-25. Hence, this means thattwo sheets of copying paper are fed simultaneously, and one of themwraps about the photosensitive member and the other exists in theconveying passage. In such a case, the counted value of the papercounter 322 is increased by 1 in step n4-34. As a result, the countednumber of the paper counter 322 is made equal to the number of copyingpaper sheets which exist in the main body 2 of the copying apparatus andshould therefore be removed before resuming the copying process. Then,in step n4-35, the above fact is stored in the paper trouble memory 368,and thereafter in step n4-36, the continuity flag 312 is reset at logic"0". Then, in step n4-37, the inhibition flag 314 is set at logic "1",and thereafter step n4-66 sets in.

When the counter 338 is not set in step n4-23 and when the detectingmeans 244 does not detect the copying paper in step n4-33, step n4-38sets in. In step n4-38, it is judged whether the third paper jam counter340 is set. When the counter 340 is set, the counter 340 performscounting in step n4-39, and thereafter, in step n4-40, it is judgedwhether the counter 340 has counted a predetermined number. When thecounter 340 has counted a predetermined number (namely, when the copyingpaper has jammed between the detecting means 234 and the detecting means236), the fact that the copying paper has jammed between the detectingmeans 234 and the detecting means 236 is stored in the paper troublememory 368 in step n4-41. Then, in step n4-42, the continuity flag 312is reset at logic "0", and in step n4-43, the inhibition flag 314 is setat logic "1". Thereafter, step n4-66 sets in.

When the counter 340 is not set in step n4-38, and when the counter 340has not counted a predetermined number in step n4-40, step n4-44 setsin. In step n4-44, it is judged whether the fourth paper jam counter 342is set. When the counter 342 is set, the counter 342 performs countingin step n4-45, and thereafter in step n4-46, it is judged whether thecounter 342 has counted a predetermined number. When the counter 342 hascounted the predetermined number (namely, when the copying paper hasjammed during the time from the arrival of the leading edge of thecopying paper at the detecting position of the detecting means 236 tothe passage of its trailing edge past this detecting position), thisfact is stored in the paper trouble memory 368 in step n4-47. Then, instep n4-48, the continuity flag 312 is reset at logic "0", and in stepn4-49, the inhibition flag 314 is set at logic "1". Thereafter, stepn4-66 sets in.

When the counter 342 is not set in step n4-44 and when the counter 342has not counted the predetermined number in step n4-46, step n4-50 setsin. In step n4-50, it is judged whether a trouble has occurred in thesorter 10. When a trouble has occurred in the sorter 10, a signalshowing this fact is fed from the detecting means 266 into theprocessing means 306. When a trouble has occurred in the sorter 10, theoccurrence of the trouble in the sorter 10 is stored in a sorter troublemember 370 included in the processing means 306 in step n4-51, and instep n4-52, the continuity flag 312 is reset at logic "0". Then, theinhibition flag 314 is set at logic "1" in step n4-53, and thereafterstep n4-66 sets in.

When no trouble has occurred in the sorter 10 in step n4-50, step n4-54sets in, and in this step, it is judged whether the second document jamcounter 346 is set. When the counter 346 is set, the counter 346performs counting in step n4-55, and thereafter, in step n4-56, it isjudged whether the counter 346 has counted a predetermined number. Whenthe counter 346 has counted the predetermined number (namely, when thedocument moved away for discharge from the transparent plate 12 in thesemi-automatic document supplying and discharging device 6 has jammedbefore it reaches the detecting device 266), the jamming of thedischarged document before reaching the detecting means 266 is stored inthe document trouble memory 366 in step n4-57. After the delay of apredetermined period of time in step n4-58, the inhibition flag 314 isset at logic "1" in step n4-59, and thereafter step n4-66 sets in. Thedelay of a predetermined period of time in step n4-58 permits thedischarging of the copying paper conveyed in the main body 2 of thecopying apparatus.

When the counter 346 is not set in step n4-54, and when the counter 346has not counted the predetermined number in step n4-56, step n4-60 setsin. In step n4-60, it is judged whether the third document jam counter348 is set. When the counter 348 is set, the counter 348 performscounting in step n4-61 and it is judged in step n4-62 whether thecounter 348 has counted a predetermined number. When the counter 348 hascounted the predetermined number (namely, when the document has jammedduring the time from the arrival of the leading edge of the dischargeddocument at the detecting position of the detecting means 266 to thetime of passage of its trailing edge past this detecting position), thisfact is stored in the document trouble memory 366 in step n4-63. Then,after the delay of a predetermined period of time in step n4-64, theinhibition flag 314 is set at logic "1" in step n4-65. Thereafter, stepn4-66 sets in.

When the counter 348 is not set in step n4-60, and when the counter 348has not counted the predetermined number in step n4-62, step n4-66 setsin.

In step n4-66, it is judged whether a signal for the performance of thecopying process, i.e. the aforesaid copying process performance signalproduced by momentarily closing the print switch 282 (FIG. 6) by hand orthe aforesaid document insertion signal produced by the detection of themanually inserted document by the detecting means 258 in thesemi-automatic document supplying and discharging device 6, is produced.When the above signal is produced in step n4-66, step n4-67 sets in, andit is judged whether the inhibition flag 314 is set at logic "1". Whenthe inhibition flag 314 is not set (namely, when the copying process isready for performance), step n4-68 sets in. In step n4-68, thecontinuity flag 312 is set at logic "1". Then, in step n4-69, thecounted number of the copy number setting counter 310 is displayed, andin step n4-70, the counted number of the copying process counter 320 isdisplayed. The counted number of the copy number setting counter 310 isdisplayed digitally in the first display means 302 (FIG. 6), and thecounted number of the copying process counter 320 is displayed digitallyin the second display means 304 (FIG. 6). When the aforesaid signal isnot produced in step n4-66, the process directly goes to step n4-69 andn4-70.

On the other hand, when the inhibition flag 314 is set at logic "1" instep n4-67 (namely when the performance of the copying process isimpossible), step n4-71 sets in. In step n4-71, it is judged whether atrouble has occurred in the various constituent elements of the copyingapparatus. When a trouble has occurred in the constituent elements, thedatum stored in the trouble memory 362 is displayed in step n4-72. Suchdisplaying may include the energization of the serviceman call lamp 298(FIG. 6) and the indication in the first display means 302 (FIG. 6) of aspecific constituent element which has got out of order. Such a displayin the first display means 302 may be "L1" as shown in FIG. 12-A whensuch an element is the document illuminating lamp 118.

When no trouble has occurred in the constituent elements in step n4-71,step n4-73 sets in. In step n4-73, it is judged whether the key card 276(FIGS. 1 and 2) is inserted in the key card inserting section 274 (FIGS.1 and 2). When the key card 276 is not inserted, the datum stored in thekey card memory 364 is displayed in step n4-74. Such a displaying may bethe energization of the key card lamp 294 (FIG. 6).

When the key card 276 is inserted in step n4-73, step n4-75 sets in. Instep n4-75, it is judged whether a trouble has occurred in the conveyingof the document in the semi-automatic document supplying and dischargingdevice 6. When a trouble has occurred in the conveying of the document,the datum stored in the document trouble memory 366 is displayed in stepn4-76. Such a displaying may include the energization of the troublelamp 300 and the displaying in the first display means 302 (FIG. 6). Thedisplay in the first display means 302 may, for example, be "D1" whichis a combination of "D" showing the document and the number "1"indicating the place of jamming (meaning the upstream side of thedetecting means 264), as illustrated in FIG. 12-B.

When no trouble has occurred in the conveying of the document in stepn4-75, step n4-77 sets in. In step n4-77, it is judged whether a troublehas occurred in the conveying of the copying paper in the main body 2 ofthe copying apparatus. When a trouble has occurred in the conveying ofthe copying paper, the datum stored in the paper trouble memory 368 isdisplayed in step n4-78, and in step n4-79, the counted number of thepaper counter 322 is displayed. Displaying of the datum stored in thepaper trouble memory 368 may include the energization of the troublelamp 300 (FIG. 6) and displaying in the first display means 302 (FIG.6). The display in the first display means 302 may be a combination of"P" showing the paper and the number "2" indicating the place of jamming(or wrapping) (the number 2 means a place between the detecting means232 and the detecting means 234). The counted number of the papercounter 322 is digitally displayed in the second display means 304 (FIG.6), as shown in FIG. 12-C. The counted number, such as "2", of the papercounter 322 displayed digitally in the second display means 304 meansthe number of copying paper sheets which exist in the main body 2 of thecopying apparatus and should be removed before resuming the copyingprocess.

When no trouble has occurred in the conveying of the copying paper instep n4-77, step n4-80 sets in, and the datum of the sorter troublememory 370, which relates to the trouble in the sorter 10, is displayed.Such displaying may include the energization of the trouble lamp 300(FIG. 6) and displaying in the first display means 302 (FIG. 6). Thedisplay in the first display means 302 may, for example, be "S" whichmeans the sorter, as illustrated in FIG. 12-D.

In the trouble display control system described hereinabove, thefollowing fact should be noted. Conventional copying apparatuses, too,are adapted to indicate the occurrence of various troubles in theapparatus to the operator. In the conventional apparatuses, however,displaying of troubles is effected before the manual operation of theprint switch (or the manual insertion of the document), and therefore,the operator tends to be embarassed or surprised at such displaying andbe unable, because of this mental disturbance, to properly cope with thetroubles. In contrast, as will be easily appreciated by reference tosteps n4-66 and n4-67, troubles are displayed only after the operationof the operator, i.e. the manual operation of the print switch 284 (FIG.6) or the manual insertion of the document, and the undesirable tendencyseen with the conventional copying apparatuses can be avoided.

CONTROLLING ON THE BASIS OF THE TEMPERATURE OF THE SURFACE OR ITSVICINITY OF THE PHOTOSENSITIVE MEMBER

In the electrostatic copying apparatus improved in accordance with thisinvention, the electrical heating means 237 for heating thephotosensitive member 20 as described hereinabove is provided. Theelectrical heating means 237 (FIG. 4) is constructed of, for example, aheater. With reference to FIG. 4, the electrical heating means 237 isdisposed beneath the transfer corona discharge device 42 within thehousing 4 (FIG. 3). Preferably, the electrical heating means 237 isdisposed in proximity to the photosensitive member 20. It can beprovided at a suitable position inwardly or outwardly of the rotatingdrum 18.

In the electrostatic copying apparatus, a control system shown in FIG.13 is provided in relation to the electrical heating means 237. Thecontrol system includes a detecting device 283 including the temperaturedetecting means 279 for detecting the temperature of the surface or itsvicinity of the photosensitive member 20 and a heating control means 500included in the processing means 306. The temperature detecting means279 can be constructed of a detecting means for example a thermistorwhose vesistance value decreases with a rise in the detectedtemperature. The output voltage of the detecting device 283 is increasedin proportion to the detected temperature of the temperature detectingmeans 279. In the illustrated embodiment, this detecting device 283 isprovided in proximity to the photosensitive member 20 downstream of thepeeling corona discharge device 46 as viewed in the rotating directionof the rotating drum 18 shown by the arrow 22 (FIG. 4). The heatingcontrol means 500 comprises a comparator 502. In this control system,the output voltage from the detecting device 283 based on thetemperature detected by the temperature detecting means 279 is fed to anon-inverted input of the comparator 502 of the heating control means500. A reference voltage V₁ is applied to a inverted input of thecomparator 502. The reference voltage V₁ is set at a voltage equal tothe output voltage from the detecting device 283 at a predeterminedtemperature (35° C. in the illustrated embodiment) at which dewformation on the surface of the photosensitive member 20 can beprevented and the charging voltage of the photosensitive member 20 canbe maintained at a right value. The output signal from the comparator502 is fed into a normally closed switch means 506 disposed in a heatingcontrol circuit 504, and the switch means 506 is opened or closed bythis output signal. In the heating control circuit 504, the electricalheating means 273 is connected to a suitable power supply E such as acommercial AC power supply through the switch means 506. Hence, when theswitch means 506 is closed, the electrical heating means 273 isenergized, and when the switch means 506 is opened, the electricalheating means 273 is deenergized.

The output voltage of the detecting device 283 which is based on thetemperature detected by the temperature detecting means 279 is also fedinto a charging control means 508 included in the processing means 306.The output signal from the charging control means 508 is fed into a highvoltage source 510 such as a high voltage transformer, and on the basisof this output, the output voltage of the high voltage source 510 iscontrolled. The charging control means 508 controls the output voltageof the high voltage source 510 on the basis of the output voltage of thedetecting device 283, and acts to increase and decrease the outputvoltage of the high voltage source 510 substantially in proportion tothe rising and falling of the output voltage of the detecting device279, or in other words, to the rising and falling of the temperaturedetected by the detecting device 279. The output signal of the highvoltage source 510 is fed into the charging corona discharge device 38.

With reference to FIGS. 4 and 13, the operation and effect of theelectrostatic copying apparatus equipped with the control systemdescribed above will be described.

When the temperature of the surface or its vicinity of thephotosensitive member 20 is below a relatively low predetermined value(35° C. in the illustrated embodiment), the output voltage from thedetecting device 283 is lower than, or equal to, the reference voltageV₁, and the output signal of the comparator 502 becomes zero. Hence theswitch means 506 is closed, and the electrical heating means 273 isenergized to thereby heat the photosensitive member 20. When thephotosensitive member 20 is heated and the temperature of its surface orits vicinity rises, the charging control means 508 controls the outputvoltage of the high voltage source 510 on the basis of the outputvoltage from the detecting device 283, and increases the output voltageof the high voltage source 510 in proportion to the rise of the abovetemperature.

On the other hand, when the photosensitive member 20 is heated by theelectrical heating means 273 and the temperature of the surface or itsvicinity of the photosensitive member 20 exceeds a predetermined value(35° C. in the illustrated embodiment), the output voltage from thedetecting device 283 becomes larger than the reference voltage V₁, andthe output signal of a predetermined voltage from the comparator 502 isfed into the switch means 506. As a result, the switch means 506operates and becomes open, whereby the electrical heating means 273 isdeenergized, and the heating of the photosensitive member 20 is stopped.When the heating of the photosensitive member 20 is stopped and thetemperature of the surface or its vicinity of the photosensitive member20 drops, the charging control means 508 controls the output voltage ofthe high voltage source 510 on the basis of the output voltage from thedetecting device 283, and the output voltage of the high voltage source510 is decreased in proportion to the dropping of the temperature.

As stated hereinabove, in the electrostatic copying apparatus equippedwith the aforesaid control system, the temperature of the surface or itsvicinity of the photosensitive member 20 is maintained approximately ata predetermined value (35° C. in the illustrated embodiment) by theenergization or deenergization of the electrical heating means 273. Itis possible therefore to prevent dew formation on the surface of thephotosensitive member 20 and to obtain a copied image of good quality.

Furthermore, since the voltage applied to the charging corona dischargedevice 38 by the action of the charging control means 508 is increasedand decreased in proportion to the rise and fall of the temperature ofthe surface or its vicinity of the photosensitive member 20, the chargepotential applied to the surface of the photosensitive member 20 by thecharging corona discharge device 38 can be controlled to a right valuedepending upon the aforesaid temperature, and a copied image of goodquality can therefore be obtained.

CONTROL OF HEATING THE HEAT FIXING DEVICE

In the electrostatic copying apparatus improved in accordance with thisinvention, a control system illustrated in FIG. 14 is provided inrelation to the heat fixing device 104 (FIG. 3). The control systemfurther includes a power saving means 512 and a heating control means(not shown) included in the processing means 306, in addition to thepower switch 282 and the detecting device 281 including the temperaturedetecting means 277 for detecting the temperature of the heat fixingdevice 104. The temperature detecting means 277 is provided in contactwith, or in proximity to, the surface of the heating roller 108 (FIG. 3)in the heat fixing device 104, and detects the temperature of thesurface or its vicinity of the heating roller 108. Such a temperaturedetecting means 277 can be constructed of, for example, a thermistor.The power saving means 512 comprises a power saving switch 514 disposedon the panel 280, and produces a power saving signal when manuallyclosed. The heating control means of the processing means 306 includes amemory 516 and a first heater counter 518. A first predetermined valueT₁, a second predetermined value T₂ and a third predetermined value T₃are stored in the memory 516. The first predetermined value T₁ is set ata temperature (about 180° C. in the illustrated embodiment) which issuitable for heat fixing the toner image on the copying paper by theheat fixing device 104. The second predetermined value T₂ is set at asuitable temperature (190° C. in the illustrated embodiment) which ishigher than the first predetermined temperature value T₁ (T₁ <T₂). Thethird predetermined value T₃ is set at a suitable temperature (160° C.in the illustrated embodiment) which is higher than the softeningtemperature of the toner but is lower than the first predetermined valueT₁ (T₃ <T₁). The first heater counter 518 is comprised of a backup-typecounter, and begins counting up when the power switch 282 is closed, andbegins counting down when the power switch 282 is opened. A detaileddescription of the detecting device 281 is omitted here since it isgiven hereinafter.

In the above control system, the output signals of the power switch 282and the detecting device 281 including the temperature detecting means277 (FIG. 14) and the power saving signal of the power saving switch 514are fed into the heating control means of the processing means 306. Theoutput signal from the heating control means is fed into the switchmeans 520 and causes the opening and closing of the switch means 520.When the switch means 520 is closed, the electrical heating means 106(FIG. 14) of the heat fixing device 104 is connected to a suitable powersupply E such as a commercial AC power supply and energized. When theswitch means 520 is opened, the aforesaid connection is released todeenergize the electrical heating means 106.

The operation and effect of the heat fixing device 104 including theaforesaid control system will be described with reference to FIG. 15showing a flow chart of the method of control by the control systemdescribed above and FIG. 16 which shows changes with time of thetemperature of the surface or its vicinity of the heating roller 108.When the power switch 282 on the panel 280 is closed in step n5-1, stepn5-2 sets in. In step n5-2, it is judged whether the temperaturedetecting means 277 is out of order (for example, when the temperaturedetecting means 277 is constructed of a thermistor, whether thethermistor has breaks). When the power switch 282 is closed, theelectrical heating means 106 is energized to heat the heat fixing device104 and at the same time the waiting flag 308 included in the processingmeans 306 is set at logic "1", whereby the waiting display lamp 296(FIG. 6) is energized to indicate that the heat fixing device 104 is ina preparatory condition. The waiting flag 308 is reset at logic "0" oncethe temperature of the heat fixing device 104 detected by thetemperature detecting means 277 has exceeded the second predeterminedvalue T₂ as a result of heating by the electrical heating means 106.Hence, the waiting display lamp 296 is deenergized. The waiting flag 308is set when the power saving switch 514 is closed or the power switch282 is opened. Moreover, when the power saving switch 514 is opened andthe temperature detected by the temperature detecting means 277 hasexceeded the first predetermined value T₁, the waiting flag 308 isreset.

When in step n5-2 it is judged that the temperature detecting means 277is out of order, step n5-3 sets in, and the service man call lamp 298 onthe panel 280 is turned on, thus showing that some trouble has occurredin the copying apparatus. On the other hand, when it is judged in stepn5-2 that the temperature detecting means 277 is not out of order, stepn5-4 sets in, and the second predetermined value T₂ (about 190° C.)stored in the memory 516 in the heating control means is read out, andset [When the predetermined value T₂ has been set, the electricalheating means 106 is controlled based on the signal from the detectingdevice 281 such that the temperature of the surface or its vicinity ofthe heating roller 108 is adjusted substantially to the secondpredetermined value T₂ (about 190° C.)]. Then, step n5-5 sets in, andcounting up of the counter 518 of the heat control means is started.Furthermore, step n5-6 sets in, and it is judged in this step whetherthe counter 518 has counted a predetermined number. The predeterminednumber is the number of counts corresponding to a first predeterminedtime W₁ from time t₀ to time t₂ in FIG. 16. Hence when the counter 518has counted the predetermined number, the first predetermined time W₁elapses. This first predetermined time W₁ is, for example, 10 to 15minutes. When in step n5-6 it is judged that the counter 518 has notcounted the predetermined number, step n5-2 again sets in. When duringthe counting of the counter 518, the heat fixing device 104 is heated tocause the temperature of the surface or its vicinity of the heatingroller 108 to exceed the second predetermined value T₂, the waiting flag308 is reset at logic "0" on the basis of the signal from thetemperature detecting means 277. As a result, the waiting display lamp296 is deenergized to show that the copying process is in condition forperformance. Although at this time the ambient temperature of the heatfixing device 104 is slightly lower than that in an optimal condition,the temperature of the surface or its vicinity of the heating roller 108after the deenergization of the waiting display lamp 296 becomes thesecond predetermined value T₂ which is higher than the firstpredetermined value T₁. Hence, the toner image can be fixedsatisfactorily.

On the other hand when in step n5-6 it is judged that the counter 518has counted the predetermined number, step n5-7 sets in, and the firstpredetermined value T₁ (about 180° C.) stored in the memory 516 of theheating control menas is read out. Thus, instead of the secondpredetermined value T₂, the first predetermined value T₁ is set [whenthe predetermined value T₁ has been set, the electrical heating means106 is controlled on the basis of the signal from the detecting device281 such that the temperature of the surface or its vicinity of theheating roller 108 is adjusted substantially to the first predeterminedvalue T₁ (about 180° C.)]. At this time, the counter 518 keepsmaintaining the aforesaid predetermined count number. Thus, theelectrical heating means 106 is controlled such that the temperature ofthe surface or its vicinity of the heating roller 108 is adjustedsubstantially to the first predetermined value T₁. After the time t₃,this temperature is maintained substantially at the first predeterminedvalue T₁, and the temperature of the ambient atmosphere is maintained atan optimal value.

Accordingly, when the power switch 282 is closed to apply power, thetemperature of the surface or its vicinity of the heating roller 108 ismaintained substantially at the second predetermined value T₂ higherthan the first predetermined value T₁ even during the time from t₁ tot₂, and thereafter is maintained substantially at the firstpredetermined value T₁ after the time t₃. Thus, it is maintained at atemperature optimal for the heat fixing of the toner image.

When the first predetermined value T₁ is set in step n5-7, step n5-8sets in. In step n5-8, it is judged whether the power saving switch 514is closed. When it is judged in step n5-8 that the power saving switch514 is not closed, step n5-9 sets in. In step n5-9, it is judged whetherthe power switch 282 is closed. When it is judged in step n5-9 that thepower switch 282 is closed, step n5-13 sets in, and it is judged in thisstep whether the counter 518 is zero. When it is judged in step n5-13that the counter 518 is not zero, steps n5-7 again sets in. Hence, afterthe time t₃, the temperature of the surface or its vicinity of theheating roller 108 is maintained substantially at the firstpredetermined value T₁ unless the power saving switch 514 or the powerswitch 282 is closed.

On the other hand, when it is judged in step n5-8 that the power savingswitch 514 is closed, step n5-10 sets in, and the third predeterminedvalue T₃ (about 160° C.) stored in the memory 516 in the heating controlmeans is read out. As a result, the third predetermined value T₃ is setinstead of the first predetermined value T₁ [when the predeterminedvalue T₃ has been set, the electrical heating means 106 is controlled onthe basis of the signal from the detecting device 281 such that thetemperature of the surface of its vicinity of the heating roller 108 isadjusted substantially to the third predetermined value T₃ (about 160°C.)]. When the third predetermined value T₃ has been set in step n5-10,step n5-11 follows. In step n5-11, it is judged whether the power savingswitch 514 is opened. When it is judged in step n5-11 that the powersaving switch 514 is not opened, the step n5-10 again sets in. Hence,when the power saving switch 514 is closed after the time t.sub. 4, theelectrical heating means 106 is controlled such that the temperature ofthe surface or its vicinity of the heating roller 108 is adjustedsubstantially to the third predetermined value T₃. After the time t₅,this temperature is maintained substantially at the third predeterminedvalue T₃. When the power saving switch 514 is closed, the waiting flag308 is reset at logic "0" to energize the waiting display lamp 296 (FIG.6), thus showing that the heat fixing device 104 is in a preparatorycondition.

On the other hand, when it is judged in step n5-11 that the power savingswitch 514 is opened, step n5-7 again sets in. In step n5-7, the firstpredetermined value T₁ stored in the memory 516 is read out, and thefirst predetermined value T₁ is set instead of the third predeterminedvalue T₃ (when the predetermined value T₁ is set, the electrical heatingmeans 106 is controlled such that the temperature of the surface or itsvicinity of the heating roller 108 is adjusted substantially to thefirst predetermined value T₁). Thus, when the power saving switch 514 isclosed, and thereafter opened at time t₆, the electrical heating means106 is controlled such that the temperature of the surface or itsvicinity of the heating roller 108 is adjusted substantially to thefirst predetermined value. After the time t₇, this temperature ismaintained substantially at the first predetermined value T₁. When thepower saving switch 514 is opened, and by the heating of the electricalheating means 106, the temperature of the heat fixing device 104detected by the temperature detecting means 277 (FIG. 14) exceeds thefirst predetermined value T₁, the waiting flag 308 is reset at logic "0"to deenergize the waiting display lamp 296, thus showing that thecopying process is in a preparatory condition.

When in step n5-9 it is judged that the power switch 282 is not closed,step n5-12 sets in, and the counting down of the counter 518 is started.The count down of the counter 518 is one from the predetermined numbermaintained in step n5-5. When the counting down of the counter 518 isperformed, step n5-9 again sets in. Hence, when the power switch 282 isopened at time t₈, the counting down of the counter 518 is effected, andthe copying apparatus is cut off from the power supply to deenergize theelectrical heating means 106. Since the power supply is turned off uponthe opening of the power switch 282, the waiting flag 308 is reset atlogic "0" and thus the waiting display lamp 296 is also deenergized. Ifit is judged in step n5-9 that the power switch 282 is closed before thenumber held by the counter 518 becomes zero by the counting down of thecounter 518 from the predetermined number in step n5-12 (that is to say,before the lapse of a second predetermined time W₂ to be described afterthe opening of the power switch 282), step n5-13 sets in. In step n5-13,it is judged whether the counted value of the counter 518 is zero.Thereafter, step n5-7 again sets in, and the first predetermined valueT₁ is set in the heating control means. In this case, the counting up ofthe counter 518 is also started although it is not shown in the flowchart. The counting up can be carried out from the count down numberkept in the counter 518 to the predetermined number. Hence, when at timet₉ after the opening of the power switch 282 but before the lapse of thesecond predetermined time W₂, the power seitch 282 is again closed toturn on the power supply, the electrical heating means 106 is controlledsuch that the temperature of the surface or its vicinity of the heatingroller 108 is adjusted substantially to the first predetermined valueT₁. The second predetermined time W₂ is the time required for thecounter 518 to count down from the predetermined number to zero, and is,for example, 10 to 15 minutes. When the power switch 282 is closed, thewaiting flag 308 is set at logic "1" to energize the waiting displaylamp 296. When the heating by the electrical heating means 106 causesthe temperature detected by the temperature detecting means 277 toexceed the first predetermined value T₁, the waiting flag 308 is resetto logic "0" to deenergize the waiting display lamp 296. On the otherhand, when, it is judged in step n5-9 that the power switch 282 isclosed, after the counter 518 has performed counting down and the numberkept by the counter 518 has become zero in step n5-12 (in other words,after the second predetermined time W₂ has elapsed after the opening ofthe power switch 282), step n5-13 sets in. In step n5-13, it is judgedwhether the counter 518 is zero, and thereafter step n5-2 agains setsin. Accordingly, when at time t₁₀ which is after the opening of thepower switch 282 and further elapsing of the second predetermined periodof time W₂, the power switch 282 is again closed to turn on the powersupply, the electrical heating means 106 is controlled such that thetemperature of the surface of its vicinity of the heating roller 108 isadjusted substantially to the second predetermined value T₂ which ishigher than the first predetermined value T₁. A detailed description ofthe controlling of the electrical heating means 106 on the basis of thesignal from the detecting device 281 including the temperature detectingmeans 277 is omitted here since it is given hereinafter.

In the illustrated embodiment, the first predetermined time W₁ and thesecond predetermined time W₂ are measured by one backup-type counter518. If desired, two such counters may be used so that one of them isused to measure the first predetermined time W₁, and the other tomeasure the second predetermined time W₂.

As stated hereinabove, in the heat fixing device 104 equpped with thecontrol system described above, the temperature of the surface or itsvicinity of the heating roller 108 is usually kept substantially at thesecond predetermined value T₂ higher than the first predetermined valueT₁ suitable for heat fixing after the power supply has been turned on,and thereafter it is maintained substantially at the first predeterminedvalue T₁. It is possible therefore to bring the temperature of thesurface or its vicinity of the heating roller 108 and the ambienttemperature to a temperature suitable for heat fixing within a shortperiod of time, and the waiting time after the application of power canbe shortened.

Furthermore, since the temperature of the surface or its vicinity of theheating roller 108 is maintained substantially at the thirdpredetermined value T₃ lower than the first predetermined value T₁suitable for heat fixing by the operation of the power saving means 512,power consumption can be reduced by utilizing the power saving meanswhen there is a considerable time interval between copying cycles.

Furthermore, when the power supply is again turned on before the lapseof the second predetermined period of time W₂ after the turning off ofthe power supply (the opening of the power switch 282), the temperatureof the surface or its vicinity of the heating roller 108 is maintainedsubstantially at the first predetermined value T₁. Accordingly, theaforesaid temperature and the ambient temperature can be brought to avalue suitable for heat fixation within short period of time.

CONTROL OF POWER DISTRIBUTION

In the electrostatic copying apparatus imporved in accordance with thisinvention, an control system shown in FIG. 14 is further provided inrelation to the heat fixing device 104 (FIG. 3), the documentilluminating lamp 118 and a drive motor 522 constituting a main electricmotor (which is a drive source for the copying apparatus and drives theoptical device 116, the rotating drum 18, the copying paper conveyingmeans 50, etc.). Again with reference to FIG. 14, this control systemcomprises a power control means (not shown) included in the processingmeans 306. The power control means includes a memory 524, a decadecounter 526 and a second heat counter 528. Predetermined values "4", "6"and "9" are stored in the memory 524. These predetermined values "4","6" and "9" are used to control the amount of an electric currentsupplied to the electrical heating means, as will be described in detailhereinafter.

In the aforesaid control system, the output signal from the powercontrol means of the processing means 306 is supplied to the switchmeans 520 (the switch 520 is opened and closed by the output signal fromthe heating control means as described hereinabove), and the switchmeans 520 is opened and closed by this output signal. The output signalfrom the processing means 306 is supplied to the switch means 530 and532 to open or close the switch means 530 and 532. The switch means 530serves to control the document illuminating lamp 118. When the switchmeans 530 is closed, the document illuminating lamp 118 is connected toa suitable power supply E such as a commercial AC power supply and thusenergized. Furthermore, upon the opening of the switch means 530, theaforesaid connection is released and the document illuminating lamp 118is deenergized. On the other hand, the switch means 532 serves tocontrol the drive motor 522. When the switch means 532 is closed, thedrive motor 522 is connected to the aforesaid power supply E, and whenthe switch means 532 is open, the aforesaid connection is released, andthe drive motor 522 is deenergized. It will be easily appreciated fromthe foregoing description that an electric power from a power supply Esuch as a commercial AC power source which is a single power supplysource is supplied to the electrical heating means 106, the documentilluminating lamp 118 and the drive motor 522. The processing means 306is also connected to the power supply E.

The operation and effect of the electrostatic copying apparatus equippedwith the aforesaid control means will be described with reference toFIG. 17 showing the flow chart of the method of controlling according tothe control system described above and FIG. 18. In the followingdescription, a commercial AC power supply is used as the power supply E.When the power supply is turned on, it is first judged in step n6-1whether the voltage of the power supply E is zero cross. When it isjudged that it is not zero cross, the original state is revived. On theother hand, when it is judged that the voltage is zero cross, step n6-2sets in. In step n6-2, it is judged whether the drive motor 522 isenergized (therefore, whether the switch 532 is closed). When it isjudged in step n6-2 that the drive motor 522 is energized, the next stepn6-3 sets in, and in this step, it is judged whether the documentilluminating lamp 118 is energized (therefore, whether the switch 530 isclosed). When in step n6-3 it is judged that the document illuminatinglamp 118 is energized, step n6-4 sets in. In step n6-4, thepredetermined value "4" stored in the memory 524 in the power controlmeans is read out and set. On the other hand, when it is judged in stepn6-3 that the document illuminating lamp is not energized, step n6-5sets in. In step n6-5, the predetermined value "6" stored in the memory524 in the power control means is read out and set. Furthermore, when itis judged in step n6-2 that the drive motor 522 is not energized, stepn6-6 sets in. In step n6-6, the predetermined value "9" stored in thememory 524 in the power control means is read out and set. Accordingly,when the drive motor 522 and the document illuminating lamp 118 are notenergized, the predetermined value "9" is set, and when the drive motor522 is energized, the predetermined value "6" is set. Furthermore, whenthe drive motor 522 and the document illuminating lamp 118 areenergized, the predetermined value "4" is set.

After the predetermined value has been set in step n6-4, n6-5 or n6-6,step n6-7 sets in and the counting of the decade counter 526 is started.The decade counter 526 counts up from 0 to 9 for each half cycle of thepower supply E. When the counting of the decade counter 526 begins, stepn6-8 then sets in, and it is judged in this step whether the decadecounter 526 has counted up to 9 and produced a carry signal. When it isjudged in step n6-8 that the carry signal has been produced, step n6-9sets in. In step n6-9, the aforesaid predetermined value is transferredto the second heater counter 528 and store. More specifically, when thepredetermined value "4" is set in step n6-4, this predetermined value"4" is stored in the heater counter 528. When the predetermined value"6" is set in step n6-5, the predetermined value "6" is stored in theheater counter 528. When the predetermined value "9" is set in stepn6-6, this predetermined value "9" is stored in the heater counter 528.Thereafter, step n6-10 sets in, and it is judged in this step whetherthe value of the heater counter 528 is zero. The heater counter 528counts down one by one from the aforesaid stored value for each halfcycle of the power supply E. When it is judged in step n6-8 that thecarry signal is not produced, step n6-8 is followed by step n6-10. Whenit is judged in step n6-10 that the heater counter 528 is not zero, stepn6-11 sets in and the heater counter 528 counts down by one. Then, stepn6-12 sets in, and it is judged in this step whether the detectedtemperature of the heat fixing device 104 (therefore, the temperature ofthe surface or its vicinity of the heating roller 108 which is detectedby the temperature detecting means 277) is equal to, or below, theprescribed value. [In more detail, when the first predetermined value(about 180° C.) is set in the heating control means, it is judgedwhether the detected temperature is equal to, or below, the firstpredetermined value; when the second predetermined value (about 190° C.)is set, it is judged whether the detected temperature is equal to orbelow the second predetermined value; and when the third predeterminedvalue (about 160° C.) is set, it is judged whether the detectedtemperature is equal to or lower than the third predetermined value.]When it is judged in step n6-12 that the detected temperature is equalto or lower than the preset value, step n6-13 sets in and the electricalheating means 106 is energized (the switch means 520 is closed by thesignals from the power control mean and the heating control means).Thereafter, the process returns to step n6-11. On the other hand, whenit is judged in step n6-12 that the detected temperature is not equalto, or below, the preset value, step n6-14 sets in, and the electricalheating means 106 is deenergized (the switch means 520 is opened by thesignals from the heating control means irrespective of the signal fromthe power control means). Thereafter, the process returnes to step n6-1.When the aforesaid step is performed, and it is judged in step n6-10that the counted number of the heater counter 528 is zero, step n6-14sets in, and the electrical heating means 106 is deenergized (the switchmeans 520 is opened by the signal from the power control meansirrespective of the signal from the heating control means). Thereafter,step n6-1 again sets in. Thereafter, the aforesaid operation is repeateduntil the power supply of the copying apparatus is turned off. It willbe readily appreciated that in the above control system, the aboveoperation is repeated for each half cycle of the alternate current fromthe power supply E.

In the above-described flow chart, the operations performed when thepredetermined value "4" is set in step n6-4 (therefore when the drivemotor 522 and the document illuminating lamp 118 are energized), whenthe predetermined value "6" is set in the step n6-5 (therefore, when themotor 522 is energized), and when the predetermined value "9" is set instep n6-6 (therefore, when the drive motor 522 and the documentilluminating lamp 118 are not energized) are briefly as follows:

In the case of the predetermined value "4" being set, the predeterminedvalue "4" is stored in the heater counter 528 when the decade counter526 has produced a carry signal (namely, when the decade counter 526 hascounted up one by one and reached 9). After the decade counter 526 hasproduced a carry signal, it again returns to 0, and counts up one by onefrom 0. After the predetermined value "4" has been stored, the heatercounter 528 counts down one by one from the predetermined value "4" foreach half cycle of the AC current of the power supply E. Until it iscounted down to zero, the switch means 520 is closed by the signal fromthe power control means, and the current from the power supply E is fedinto the electrical heating means 106. After the counted value hasreached zero, the switch means 520 is opened by the signal from thepower control means and the supply of the current is stopped. In such acase, therefore, the current supplied to the electrical heating means isas shown by (1) in FIG. 18, and after storage in the heater counter 528,an alternate current of five half cycles is supplied to the electricalheating means 106, and during the period from the time t₁₁ to t₁₂, theelectrical heating means 106 is energized. When the decade counter 526counts up one by one for each half cycle of the power supply E and againproduces a carry signal, the aforesaid operation is repeated. It will bereadily appreciated from the foregoing statement that by the carrysignal of the decade counter 526, ten half cycles of the power supply Eform one cycle Q (for example, from the time t₁₁ to the time t₁₃). Whenthe predetermined value "4" is set, the amount of current perpredetermined period supplied to the electrical heating means 106becomes one-half of the amount of current per predetermined period fromthe power supply E by the action of the power control means. When theaforesaid detected temperature is higher than the preset value, theswitch means 520 is opened by the signal from the heating control means.Accordingly, even when the counted value of the heater counter 528 isnot zero, the electrical heating means 106 is not energized.

When the predetermined value "6" is set, the predetermined value "6" isstored in the heater counter 528 when the decade counter 526 hasproduced a carry signal. After the predetermined value "6" has beenstored, the heater counter 528 counts down one by one from thepredetermined value "6" for each half cycle of the alternate current ofthe power supply E. Until the counted value becomes zero as a result ofcounting down, the switch means 520 is closed by the signal from thepower control means, and the current from the power supply E is suppliedto the electrical heating means 106. After the counted value has becomezero, the switch means 520 is opened by the signal from the powercontrol means, and the supply of the current is stopped. Accordingly, inthis case, the current supplied to the electrical heating means 106 isas shown by (2) in FIG. 18, and after storage in the heater counter 528,an alternate current of seven half cycles is supplied to the electricalheating means 106, and thus, the electrical heating means 106 isenergized during the period from the time t₁₁ to the time t₁₄. When thedecade counter 526 counts up one by one for every half cycle of thepower supply E and again produces a carry signal, the aforesaidoperation is repeated. Thus, when the predetermined value "6" is set,the amount of current per predetermined period supplied to theelectrical heating means 106 becomes 7/10 of the amount of current perpredetermined period from the power supply E by the action of the powercontrol means. In this case, too, when the detected temperature is theabove the predetermined value, the switch means 520 is opened by thesignal from the heating control means. Hence, even when the countednumber of the heater counter is not zero, the electrical heating means106 is not energized.

Furthermore, when the predetermined value "9" is set, the predeterminedvalue "9" is stored in the heater counter 528 when the decade counter526 has produced a carry signal. After the predetermined value "9" hasbeen stored, the heater counter 528 counts down one by one from thepredetermined value "9" for each half cycle of the alternate currentfrom the power supply E. Until the counted value becomes zero as aresult of counting down, the switch means 520 is closed by the signalfrom the power control means, and the current from the power supply E issupplied to the electrical heating means 106. Since the predeterminedvalue is "9", the current supplied to the electrical heating means 106is as shown by (3) in FIG. 18, and after storage in the heater counter528, an alternate current of 10 half cycles is supplied to theelectrical heating means, and thus, the electrical heating means 106 isenergized during the period from the time t₁₁ to the time t₁₃. When thedecade counter 526 counts up one by one for each half cycle of the powersupply E and again produces a carry signal, the above operation isrepeated. When the predetermined value "9" is set, the amount of currentper predetermined period supplied to the electrical heating means 106becomes substantially equal to the amount of current per predeterminedperiod from the power supply E by the action of the power control means.In this case, too, the switch means 520 is opened by the signal from theheating control means when the detected temperature is above theprescribed value. Hence, the electrical heating means 106 is notenergized.

As stated hereinabove, in the electrostatic copying apparatus equppedwith the control system described above, when the document illuminatinglamp 118 and the drive motor 522 are deenergized, the amount of currentper predetermined period supplied to the electrical heating means 106 isgreatest, and its power consumption is greatest. When the drive motor522 is energized, the amount of current per predetermined period issmaller than in the above-described instance, and the power consumptionis of a medium degree. When the drive motor 522 and the documentilluminating lamp 118 are energized, the amount of current perpredetermined period of time is smallest, and the power consumption issmallest. Accordingly, in the aforesaid electrostatic copying apparatus,the power consumption increases as a result of the energization of thedrive motor 522 and the document illuminating lamp 118, but the overallincrease of the power consumption in the entire copying apparatus can beprevented by reducing the power consumption of the electrical heatingmeans 106. This is effective especially when there is used a powersupply having a restricted maximum power consumption, such as acommercial AC power supply. Furthermore, since the maximum power issupplied to the electrical heating means 106 immediately afterapplication of power when the drive motor 522 and the documentilluminating lamp 118 are deenergized, the time required until thetemperature of the surface or its vicinity of the heating roller 108reaches a value suitable for the fixation of a toner image (the waitingtime) can be shortened.

It will be clear from FIG. 18 that in the illustrated embodiment, theamount of current per predetermined period supplied to the electricalheating means 106 is controlled by using a half cycle of the powersupply E as one unit. If desired, the amount of current may becontrolled as shown in FIG. 19. In FIG. 19, the alternate current of thepower supply is controlled in each half cycle. As regards the AC currentshown in FIG. 19, that part of the current which corresponds to theperiod from the time t₁₅ to the time t₁₆ and that part of the currentwhich corresponds to the period from the time t₁₇ to the time t₁₈ aresupplied to the electrical heating means 106 as a result of the openingand closing of the switch means 520 by the signal from the power controlmeans. By controlling the current as shown in FIG. 19, substantially thesame effect as in the case of FIG. 18 can be obtained.

In the illustrated embodiment, the power consumption of the electricalheating means is controlled according to the power consumption of thedrive motor 522 and the document illuminating lamp 118 which consume arelatively great deal of power. If desired, the power consumed by theelectrical heating means 106 can also be controlled according to thepower consumption of the electric heating means 237 (FIG. 4), theelectric motor 188 for the semiautomatic document supplying anddischarging device, a fan motor (not shown) for cooling the documentilluminating lamp, etc. in addition to the above. In this case, theamount of current per predetermined period supplied to the electricalheating means 106 may be decreased stepwise according to the number ofelectrical means (the drive motor 522, the document illuminating lamp118, the electric motor 188, the electrical heating means 237, etc.).

ELECTRICAL DETECTING DEVICE

In the electrostatic copying apparatus improved in accordance with thisinvention, an electrical detecting device shown in FIG. 20 is used asthe aforesaid detecting device 281 (FIG. 14) provided in relation to theheat fixing device 104 (FIG. 3). With reference to FIG. 20, thiselectrical detecting device includes a first linear-connected circuitportion 534, a second linear-connected circuit portion 536, a switchingcontrol means 538 included in the processing means 306, a comparisonmeans 540 and a DC power supply E₁. The first linear-connected circuitportion 534 includes the aforesaid temperature detecting means 277(constituting an electrical detecting element) such as a thermistor fordetecting the temperature of the surface, or its vicinity, of theheating roller 108, and a variable voltage dividing circuit 542connected in series to the temperature detecting means 277. The variablevoltage dividing circuit 542 has resistance elements R₁, R₂, R₃ and R₄and transistors Tr₁, Tr₂ and Tr₃ constituting switching means. Theresistance elements R₁, R₂, R₃ and R₄ are connected to each other inseries. The transistor Tr₁ is connected parallel to a series circuitportion composed of the resistance elements R₂, R₃ and R₄, and thetransistor Tr₂ is connected parallel to a series circuit portioncomposed of the resistance elements R₃ and R₄. The transistor Tr₃ isconnected parallel to the resistance element R₄. The bases of thesetransistors Tr₁, Tr₂ and Tr₃ are connected respectively to outputterminals P₁, P₂ and P₃ of the switching control means 538 throughresistance elements R₅, R₆ and R₇. The switching control means 538 willbe described in detail hereinafter. The second linear-connected circuitportion 536 has resistance elements R₈ and R₉ connected to each other inseries. The second linear-connected circuit portion 536 and theaforesaid first linear-connected circuit portion 534 are connectedparallel to each other across the DC power supply E₁. The comparisonmeans 540 is constructed of a comparator 544. The non-inverted inputterminal of the comparator 544 is connected to a point of connectionbetween the temperature detecting means 277 and the variable voltagedividing circuit 542 in the first linear-connected circuit portion 534,and its inverted input terminal is connected to a point of connectionbetween the resistance elements R₈ and R₉ in the second linear-connectedcircuit portion 536. On the other hand, the output terminal of thecomparator 544 is connected to an input terminal IN of the heatingcontrol means included in the processing means 306. Thus, when a firstdivided voltage at the point of connection between the temperaturedetecting means 277 and the variable voltage dividing circuit 542becomes equal to, or below, a second divided voltage (acting as areference voltage) of the point of connection between the resistanceelements R₈ and R₉, a signal of logic "0" is produced in the comparator544. This logic "0" signal is fed into the heating control means formedof memory 516 and first heater counter 518 (FIG. 14). When the firstdivided voltage becomes higher than the second divided voltage, a signalof logic "1" is produced in the comparator 544 and is fed to the heatingcontrol means. A signal produced in the heating control means on thebasis of the signal from the comparator 544 is fed to the switch means520, and the switch means 520 is opened or closed on the basis of thissignal. As stated above, when the switch means 520 is closed, theelectrical heating means 106 (FIGS. 3 and 14) is energized. When theswitch means 520 is opened, the electrical heating means 106 isdeenergized. The switch means 520 is also opened or closed by the powercontrol means as stated hereinabove.

Now, the switching control means 538 will be described. FIG. 21 depictsoutput voltage as a function of time. The signals shown in FIG. 21 aredelivered respectively from the output terminals P₁, P₂ and P₃ of theswitching control means 538. A high level signal of a cycle M with apulse width M₁ shown by (1) in FIG. 21 is delivered from the outputterminal P₁. From the output terminal P₂, a high level signal of a cycleM with a pulse width M₂ as shown by (2) in FIG. 21 is delivered. Thehigh level signal with a pulse width M₂ is delivered according to thefalling of the high level signal with a pulse width M₁. Furthermore, ahigh level signal of a cycle M having a pulse width M₃ shown by (3) inFIG. 21 is delivered from the output terminal P₃. The high level signalwith a pulse width M₃ is delivered according to the falling of the highlevel signal with a pulse width M₂. In the illustrated embodiment, thepulse widths M₁, M₂ and M₃ of the high level signals are the same andset at one-fourth of the cycle M. The resistance values of theresistance elements R₁, R₂, R₃ and R₄ of the variable voltage dividingcircuit 542 are selected such that in a first timing period TM₁ (when ahigh level signal is not delivered from the switching control means538), the first divided voltage does not become lower than the seconddivided voltage unless the resistance value of the temperature detectingmeans 277 becomes larger than that at the lowest conceivable temperature(-20° C. in the illustrated embodiment); that in a second timing periodTM₂ (when the high level signal with a pulse width M₁ is delivered fromthe switching control means 538), the first divided voltage does notbecome lower than the second divided voltage unless the resistance valueof the temperature detecting means 277 becomes higher than that at theaforesaid second predetermined value T₂ (about 190° C.); that in a thirdtiming period TM₃ (when the high level signal with a pulse width M₂ isdelivered from the switching control means 538), the first dividedvoltage does not become lower than the second divided voltage unless theresistance value of the temperature detecting means 277 becomes higherthan that at the aforesaid first predetermined value T₁ (about 180° C.);and that in a fourth timing period TM₄ (when the high level signal witha pulse width M₃ is delivered from the switching control means 538), thefirst divided voltage does not become lower than the second dividedvoltage unless the resistance value of the temperature detecting means277 becomes higher than that at the aforesaid third predetermined valueT₃ (about 160° C.). The second divided voltage can be set at a suitablevalue by varying the resistance values of the resistance elements R₈ andR₉.

Now, the operation and effect of the detecting device will be described.When no high level signal is delivered from the switching control means538 (during the first timing period TM₁), the transistors Tr₁, Tr₂ andTr₃ are held at cut off, and the current from the DC power supply E₁flows through the temperature detecting means 277 and the resistanceelements R₁, R₂, R₃ and R₄. In this case, therefore, the voltage betweenthe two terminals of the series circuit portion composed of theresistance elements R₁, R₂, R₃ and R₄ is the first divided voltage, andin the comparator 544, this first divided voltage is compared with thesecond divided voltage. When it is found that the first divided voltageis higher than the second divided voltage [in other words, when thedetected temperature of the temperature detecting means 277 is higherthan the lowest conceivable temperature (-20° C.)], the output signal ofthe comparator 544 becomes logic "1". When the first divided voltage isequal to, or lower than, the second divided voltage [in other words,when the detected temperature of the temperature detecting means 277 isequal to, or lower than, the lowest conceivable temperature; but sincesuch an instance is not conceivable, when a trouble (such as wire breaksif a thermistor is used) occurs in the temperature detecting means 277],the output signal of the comparator 544 becomes logic "0". It ispossible therefore to determine by the output singal from the comparator544 during the first timing period TM₁ whether the temperature detectingmeans 277 gets out of order.

When the high level signal with a pulse width M₁ is delivered from theswitching control means 538 (during the second timing period TM₂), thetransistor Tr₁ conducts, and the current from the DC power source E₁flows through the temperature detecting means 277, the resistanceelement R₁ and the transistor Tr₁. Hence, in this case, the voltagebetween the two terminals of the resistance element R₁ is the firstdivided voltage, and this first divided voltage is compared with thesecond divided voltage in the comparator 544. When it is found that thefirst divided voltage is higher than the second divided voltage [inother words, when the detected temperature of the temperature detectingmeans 277 is higher than the second predetermined value T₂ (about 190°C.)], the output signal of the comparator 544 becomes logic "1". Whenthe first divided voltage is equal to, or lower than, the second dividedvoltage [in other words, when the detected temperature of thetemperature detecting means 277 is equal to, or lower than, the secondpredetermined value T₂ (about 190° C.)], the output signal of thecomparator 544 becomes logic "0". Thus, it is possible to determine bythe output signal from the comparator 544 during the second timingperiod TM₂ whether the detected temperature of the temperature detectingmeans 277 is equal to, or lower than, the second predetermined value T₂.

When the high level signal with a pulse width M₂ is delivered from theswitching control means 538 (during the third timing period TM₃), thetransistor Tr₂ conducts, and the current from the DC power supply E₁flows through the temperature detecting means 277, the resistanceelements R₁ and R₂ and the transistor Tr₂. In this case, therefore, thevoltage between the two terminals of the series circuit portion composedof the resistance element R₁ and R₂ is the first divided voltage, andthis first divided voltage is compared with the second divided voltagein the comparator 544. When the first divided voltage is found to behigher than the second divided voltage [in other words, when thedetected temperature of the temperature detecting means 277 is higherthan the aforesaid first predetermined value T₁ (about 180° C.)], theoutput signal of the comparator 544 becomes logic "1". When the firstdivided voltage is equal to, or lower than, the second divided voltage[in other words, when the detected temperature of the temperaturedetecting means 277 is equal to, or lower than, the first predeterminedvalue T₁ (about 180° C.)], the output signal of the comparator 544becomes logic "0". It is possible therefore to determine by the outputsignal from the comparator 544 during the third timing period TM₃whether the detected temperature of the temperature detecting means 277is equal to, or lower than, the first predetermined value T₁.

When the high level signal with a pulse width M₃ is delivered from theswitching control means 538 (during the fourth timing period TM₄), thetransistor Tr₄ conducts, and the current from the DC power source E₁flows through the temperature detecting means 277, the resistanceelements R₁, R₂ and R₃ and the transistor Tr₃. In this case, therefore,the voltage between the two terminals of the series circuit portioncomposed of the resistance elements R₁, R₂ and R₃ is the first dividedvoltage, and this first divided voltage is compared with the seconddivided voltage in the comparator 544. When it is found that the firstdivided voltage is higher than the second divided voltage [in otherowrds, when the detected temperature of the temperature detecting means277 is higher than the aforesaid third predetermined value T₃ (about160° C.)], the output signal of the comparator 544 becomes logic "1".When the first divided voltage is equal to, or lower than, the seconddivided voltage [in other words, when the detected temperature of thetemperature detecting means 277 is equal to, or lower than, the thirdpredetermined value T₃ (about 160° C.)], the output signal of thecomparator 544 becomes logic "0". It is possible therefore to determineby the output signal from the comparator 544 during the fourth timingperiod TM₄ whether the detected temperature of the temperature detectingmeans 277 is equal to, or lower than, the third predetermined value T₃.

As stated hereinabove, in the illustrated detecting device, not only aplurality of predetermined temperatures but also a throuble in thetemperature detecting means 277 itself can be detected by a singletemperature detecting means 277. The detecting device is characterizedby the fact that a trouble in the temperature detecting means 277 can bepromptly detected.

The output signal of the comparator 544 produced as above is fed to theheating control means of the processing means 306, and the switch means520 is opened or closed by a signal produced in the heating controlmeans on the basis of the signal fed from the comparator 544. Morespecifically, when the second predetermined value T₂ (about 190° C.) isset in the heating control means, only the output signal of thecomparator 544 produced during the second timing period TM₂ is takenout. When this output signal is logic "0", an actuating signal isproduced in the heating control means to close the switch means 520. Onthe other hand, when this output signal is logic "1", an operationstopping signal is produced in the heating control means to open theswitch means 520. It will be readily seen from the foregoing descriptionthat when the second predetermined value T₂ is set, the electricalheating means 106 is controlled by the output signal of the comparator544 produced during the second timing period TM₂ , and consequently, thetemperature of the surface or its vicinity of the heating roller 108 isadjusted substantially to the second predetermined value T₂.

When the first predetermined value T₁ (about 180° C.) is set in theheating control means, only the output signal of the comparator 544produced during the third timing period TM₃ is taken out. When thisoutput signal is logic "0", the switch means 520 is closed, and whenthis output signal is logic "1", the switch means 520 is opened.Accordingly, when the first predetermined value T₁ is set, theelqctrical heating means 106 is controlled by the output signal of thecomparator 544 produced during the third timing period TM₃, andconsequently the temperature of the surface or its vicinity of theheating roller 108 is adjusted substantially at the first predeterminedvalue T₁.

When the third predetermined value T₃ (about 160° C.) is set in theheating control means, only the output singal of the comparator 544produced during the fourth timing period TM₄ is taken out. When thisoutput signal is logic "0", the switch means 520 is closed as statedhereinabove. On the other hand, when this output is logic "1", theswitch means 520 is opened. Hence, when the third predetermined value T₃is set, the electrical heating means 106 is controlled by the outputsignal of the comparator 544 produced during the fourth timing periodTM₄, and consequently, the temperature of the surface or its vicinity ofthe heating roller 108 is adjusted substantially at the thirdpredetermined value T₃.

FIG. 22 shows a modified example of the electrical detecting device. Inthis figure, substantially the same parts as those in the aforesaidembodiment are designated by the same reference numerals. In theembodiment shown in FIG. 22, the second linear-connected circuit portion536 of the electrical detecting device further comprises a parallelcircuit 546 connected in series to the resistance elements R₈ and R₉.The parallel circuit 546 has an additional resistance element R₁₀ and atransistor Tr₄ constituting an additional switching means connectedparallel to the resistance element R₁₀. The base of the transistor Tr₄is connected to the output terminal P₄ of the switching control means538 through a resistance element R₁₁. Otherwise, the structure of thedetecting device in the modified example is substantially the same asthat of the embodiment described hereinabove.

The signals shown in FIG. 23 are delivered from the output terminals P₁,P₂, P₃ and P₄ of the switch control means 538. From the output terminalP₁, a high level signal of a cycle M with a pulse width M₁ as shown by(1) in FIG. 23 is delivered. This high level signal with a pulse widthM₁ is delivered according to the falling of a high level signal with apulse width M₄ which will be described hereinafter. Substantially thesame high level signals as the aforesaid high level signal, shown by (2) and (3) in FIG. 23, are respectively delivered from the outputterminals P₂ and P₃. Furthermore, a high level signal of a cycle M witha pulse width M₄ shown by (4) in FIG. 23 is delivered from the outputterminal P₄. The high level signal with a pulse width M₄ is deliveredaccording to the falling of the high level signal having a pulse widthM₃. The resistance value of the resistance element R₁₀ in the parallelcircuit 546 is selected such that during the first timing period TM₁(when the high level signal having a pulse width M₄ is delivered fromthe switching control means 538), the first divided voltage does notbecome lower than the second divided voltage unless the resistance valueof the temperature detecting means 277 becomes higher than that at thelowest conceivable temperature (-20° C. in the illustrated embodiment).

When a high level signal with a pulse width M₄ is delivered from theswitching control means 538 in this detecting device (during the firsttiming period TM₁), the transistor Tr₄ conducts, and the current fromthe DC power supply E₁ flows through the resistance elements R₈ and R₉and the transistor Tr₄. In this case, therefore, the voltage between thetwo terminals of the resistance element R₉ is the second dividedvoltage, and in the comparator 544, this second divided voltage iscompared with the first divided voltage (which, in this case, is thevoltage between the two terminals of the seried circuit portion composedof the resistance elements R₁, R₂, R₃ and R₄). On the other hand, when ahigh level signal with a pulse width M₁, a high level signal with apulse width M₂, or a high level signal with a pulse width M₃ isdelivered from the switching control means 538 (during the second timingperiod TM₂, the third timing period TM₃ or the fourth timing periodTM₄), the transistor Tr₄ is held at cut off, and the current from the DCpower supply E₁ flows through the resistance elements R₈, R₉ and R₁₀. Inthis case, therefore, the voltage between the two terminals of theseries circuit portion composed of the resistance elements R₉ and R₁₀ isthe second divided voltage, and is compared with the first dividedvoltage in the comparator 544. Otherwise, the operation and effect ofthe detecting device in the modified example are nearly the same asthose in the embodiment illustrated in FIG. 20.

In the detecting device in the modified example described above, thesecond divided voltage is increased during the first timing period TM₁.It is possible to maintain the resistance value of the resistanceelement R₄ of the first linear-connected circuit portion 534 at a lowervalue and the resistance values of the resistance elements R₁, R₂ and R₃at higher values than in the embodiment described hereinabove. As aresult, the currents flowing through the temperature detecting means 277during the second, third and fourth timing periods TM₂, TM₃ and TM₄ canbe reduced, and the amount of heat generated in the temperaturedetecting means 277 itself can be decreased.

The illustrated embodiments have been described with regard to anexample in which the detecting device is applied to the detecting device281 including the temperature detecting means 277. If desired, it isalso possible to apply such a detecting device to the detecting device283 including the temperature detecting means 279. In the latter case,only one temperature value is preset, and therefore, the resistanceelements R₂ and R₃ and the transistors Tr₂ and Tr₃ can be omitted.

Furthermore, in the illustrated embodiments, the temperature is detectedby using the temperature detecting means 277. If desired, elements otherthan temperature can be detected by using a detecting element whoseresistance value changes with a change in the amount of detection,instead of the temperature detecting means 277.

While the present invention has been described hereinabove withreference to the accompanying drawings showing the preferred embodimentsof the copying apparatus constructed in accordance with this invention,it should be understood that the present invention is no way limited tothese specific embodiments, and various changes and modifications arepossible without departing from the scope of this invention.

What is claimed is:
 1. A heat fixing device having an electrical heatingmeans for heat-fixing a toner image on a sheet member, said heat fixingdevice comprising temperature detecting means; heating control means forcontrolling energization and deenergization of the heating means on abasis of temperature detected by said temperature detecting means; saidheating control means, before lapse of a first predetermined period oftime from application of an electric power, controlling the energizationand deenergization of said heating means on a basis of whether thedetected temperature is below a second predetermined value higher than afirst predetermined value suitable for heat fixation and thus adjustingthe detected temperature substantially to the second predeterminedvalue, and after the lapse of said first predetermined period of timefrom the application of electric power, controlling the energization anddeenergization of said heating means on the basis of whether thedetected temperature is below said first predetermined value, and thusadjusting said detected temperature substantially to said firstpredetermined value; an electric power saving means having a manuallyoperable power saving switch for producing a power saving signalaccording to the operation of the power saving switch, said heatingcontrol means controlling the energization and deenergization of saidheating means on the basis of whether said detected temperature is belowa third predetermined value lower than the first predetermined valuewhen the power saving signal is present, and thus adjusting the detectedtemperature substantially to said third predetermined value.
 2. The heatfixing device of claim 1 wherein when electric power is again appliedbefore the lapse of a second predetermined time from a time of theelectric power being off, said heating control means, even before thelapse of the first predetermined time from the application of electricpower, controls the energization and deenergization of said heatingmeans on the basis of whether the detected temperature is below thefirst predetermined value and thus adjusts the detected temperaturesubstantially to said first predetermined value.
 3. The heat fixingdevice of claim 2 wherein said second predetermined time is about 10 toabout 15 minutes.
 4. The heat fixing device of claim 1 wherein saidfirst predetermined value is about 180° C.
 5. The heat fixing device ofclaim 1 wherein said second predetermined value is about 190° C.
 6. Theheat fixing device of claim 1 wherein said third predetermined value isabout 160° C.
 7. The heat fixing device of claim 1 wherein said firstpredetermined time is about 10 to about 15 minutes.
 8. The heat fixingdevice of claim 1 further comprising a cooperating pair of rollersthrough which passes the sheet member having the toner image to beheat-fixed, and in which one of said pair of rollers is hollow and saidheating means is disposed in said one of the roller pair, and saidtemperature detecting means detects the temperature adjacent the surfaceof said one of the roller pair.
 9. A heat fixing device having anelectrical heating means for heat-fixing a toner image on a sheetmember, said heat-fixing device comprising temperature detecting means;heating control means for controlling energization and deenergization ofthe heating means on a basis of temperature detected by said temperaturedetecting means; and an electric power saving means having a manuallyoperable power saving switch for producing a power saving signalaccording to the operation of the power saving switch, wherein when saidpower saving signal is absent, said heating control means controlsenergization and deenergization of said heating means on a basis ofwhether said detected temperature is below a first predetermined valuesuitable for heat fixation and thus adjusts said detected temperaturesubstantially to said first predetermined value, and when said powersaving signal is present, said heating control means controlsenergization and deenergization of said heating means on a basis ofwhether said detected temperature is below a second predetermined valuelower than the first predetermined value, and thus adjusts the detectedtemperature substantially to said second predetermined value.
 10. Theheat fixing device of claim 9 wherein said first predetermined value isabout 180° C.
 11. The heat fixing device of claim 10 wherein said secondpredetermined value is about 160° C.